I have a 84XL, 6.9, C6, 2WD, super cab, factory air, factory cruise, tilt, and 4.10 gears. biggest problem at the moment is that the gearing is too low for north dakota speed limits. currently thinking throw a gear vendors at it and be done with it. i know an E4OD is "cheaper" but i like bulletproof. why would i buy an idi otherwise?

the larger philosophical question is whether or not it is "ok" to body swap my 75 body on to it. i am very on the fence at the moment mostly because the truck is in dang near perfect stock condition at the moment. even if i do the swap at some point i will get my hands on a set of stock steel wheels and poverty caps and drive her that way for awhile.

 

Why not just do an IDI engine swap into the 75? IDIs are pretty cheap as far as motors go, especially junkyard special motors.

 

Hi Stuart .. welcome to the idi side ..

firstly about the overdrive issue .. this is usually near the top concern for every driver of trucks of this vintage .. those who engineered them somehow never suspected the national highway speed limit would someday increase beyond 55mph ..

nowadays if you are doing 55-60 your likely to get rear ended by some teen queen checking her facebook and not paying attention .. plus it's no fun .. to be slow while your trucks way wound up going nowhere fast ..

what i found that made the difference for ME was tall tires .. it help that i have 3.55 axle stock so i am now within comfortable highway cruise range .. when i got the truck there were some wore to the cord stock steelies on there and likewise 60 was max top end and then it was uncomfortable .. 35 inch tires fit and make a big improvement in dropping rpms .. going faster .. and better milage ..

can also do the gearvenders .. actually funny you ask because we were just talking about it the other day .. here

https://www.ford-trucks.com/forums/1...rew-cab-4.html

F834

" I would re-gear my Dana 60 front axle to 3.55, buy a used 3.55 rear axle (cheaper than re-gearing) and run the ZF-5. Maybe bump up the tire size to 33" for a little extra rpm drop. That's it. I would even go so far as to trade my 4.10 axles plus the GVOD straight across for comparable 3.55 axles. That's how I feel about it after owning and driving the T-19 and GVOD for 10 years."

seems i hear about the same review often when i looked up the GVOD most aren't super thrilled with the unit .. but it will work ..

likewise the E4OD is a redheaded stepchild that nobody seems to like .. so pick your poision .. if i had a bad knee and NEEDED an auto tranny or GVOD i would probably do neither and somehow swap axleshafts from a 3.08 rear end to 8x6.5 lugs or get a drop in 3.55 and bigger tires .. BUT if i had only those two i would probably get a E40D and do a rebuild ..

Mark Kovalsky said

"I've used several master rebuild kits from Home - Transtar Industries"

here >> https://www.ford-trucks.com/forums/1...-upgrades.html

these are only $200 for seals and steels kit and i would get an upgraded TC and call it done ..

if you don't mind pulling a stick you could swap it over to a ZF5 speed manual and get it in from between 500-1000 dollars and get a .75 OD gear

but we been talking about those also and it seems they are a noisy box and use light fluid .. so for me .. i will stick with my old reliable T19 and just keep or get bigger tires ..

if your 4speed auto works good and no issues with it .. i would think about just swapping in a 3.55 rearend (easy and cheap to find) and getting 33-35 tires .. that would bring you up to speed reliably ..

alot of different choices .. none are the BEST .. depends on what your needs .. expectations .. preference .. and budget will allow ..


as for for swapping bodies .. 'my opinion' NO WAY JOSE .. would i put that heap onto a fine idi .. lol

but do what you want' it's just my personal preference i love the bullnose trucks .. i like the bumpsides the late 60's .. and old 50's are nice .. the bullnoses' .. also the new superduties .. but just me .. i'm not big into the 70's body style


depends on where you are .. but in N dakaota i imagine you could get a ragged out farm truck thats ate through with rust for 500-1000 dollars .. idk depends alot on where you'r looking ..

i know here in nashville awhile back when diesel was 4 dollars a gallon you could get ragged out trucks for that price ..

now that it's dropped back down demand is sky high for the ford diesels so the asking prices have gone up 4x again ..

but when out of s.a.g i look at other CL markets esp up north more there are a lot more cheaper trucks with alot of rust but they still run good i but as long as the frame ain't rotted .. and also you can get a 2wd easy so probably wouldn't be to hard to find a ragged out donor truck rather then tear up a nice one .. that brown trucks looks pretty nice to me

i would just drop a 460 or a 300 in the 70's truck and drive it around

Leroy

 

If you are looking for bombproof reliability - keep the C6 and switch to 3.55s. I had an 86 w/3.55 and it was good to 65 mph before it started wanting another gear. I currently have an 88 with 4.10s and a ZF5 and an 89 w/3.55s and a ZF5. The 4.10 and ZF5 will get you the same hiway rpm as a C6 and 3.55s. I didn't notice a loss in getting going with a load.
Taller tires is a good idea also, but I don't know how big you can go on a 2WD unit.
Keep your 84 as is - leave the body alone.
I run 65 mph no matter what the speed limit is. Can't imagine running 80 in a 25+ year old work truck.

 

Why would you want to remove a near-perfect two-tone, esp. a color combination rarely seen outside the southwest, with a dented body with mis-matched doors?

A ZF5 with 4.10s will run considerably lower RPMs than a C6 with 3.55s. 'Course, if you could swap to a ZF5 AND do 3.55s, you'd really notice a difference. The tranny swap would be the more economical solution, though. But whichever you choose, it'll take a long time and a lot of miles to break even, wrt. fuel cost. The real advantage will be not having the thing screaming so hard going down the road.

An E4OD would be nearly out of the question; certainly not "cheaper" than any of the above choices, given that you'd have to do a LOT of mods to get all the electronics working.

 

I vote zf5 or E4OD. If you want auto the E4OD is a decent trans, it was used for idi's on up to 7.3 powerstrokes and tweaked to form the 4r100. The E4OD will give you a lock up as well, the only thing you won't get is gear splitting but very few actually need it. The electronics are not that difficult, a donor or junkyard would suffice to get everything.

 

^^^^ "Not that difficult"? How do you suggest the OP get a speed sensor feed for the E4OD tranny controller?

 

Cruise control module. It installs inline with the speedometer cable and is what is used at least on the early E4OD's for VSS. The one in the axle is for RABS.

Motorcraft DY382, Standard SC46 or similar. Just tell them it's a 91 F250 with the 7.3 diesel and you need a VSS...

As for the body swap, I don't think the 75 body will go on the 84 frame. At least not easily. They changed a lot. I don't see it being worth it. Find an IDI and swap it into the 75 if you want an IDI.

 

I haven't ran a C6 with 3.55s but I did run a T19. Both are about 1:1 for the top gear. A 1:1 ratio trans with 3.55s and a ZF5 w/ a .79 OD (going from memory) with 4.10s will be within 100 rpm of each other at 60-65mph. As you go up in speed the rpm difference will increase

 

ZF5 diesel is actually .77. And the difference at 65 MPH is almost 300 RPM (2220/2500). Easy enough to imagine - 1.0/.77 is a lot bigger jump than 4.10/3.55.

 

this^^^.
the 75 has a 33 inch wide frame, the 84 will have a 36 inch wide frame. so none of the body mounts will line up and you will either have to fabricate mounts or drill new holes in the cab, rad support, and bed to mount it.

 

As much as I find the GVOD to be awkward, that is on a manual transmission. I am not familiar with how their units operate behind an automatic. That being said, the .80 overdrive by itself will only get you to 3.20 final drive ratio. You can drive 75mph highway speed at that gearing but it will still scream. You really need 3.55 gears AND some kind of overdrive to put you at a good cruising rpm. I don't care to advise between C6+GVOD vs. E4OD since I am a manual transmission guy, and manual vs. auto is really personal preference.

 

yea the perfect old guy pakage is too good to mess up. i just want to breath some new life into the 75. the green doors are my favorite part of that truck BTW.

at any rate if i leave the tires the way they are, just throwing a gear vendors at it nets a final of 3.20 whitch gets you 2629 RPM plus converter loss at 75. not great but it wont blow up running like that. If i also throw in 3.73 gears in the back i net a final of 2.91 with an rpm of 2390 plus slip at 75. As it currently sits with the 4.10's you are turning 2470 plus slip at 55. So 3.73 plus a gear vendors should get me real close to the desined cruising RPM.

The main reason i like the idea of the gear vendors is that i fully understand just how mutch damn work it is to change the transmission to a differnt type. If i had my way i would put a NV5600 five speed from behind a cummins powerd dodge for no clutch stick shifting fun. but i am not a big fan of how a ZF5 feels rowing thru the gears. and you cant just rev match shift them.

maybe i am just hard to please?

 

glad we were able to talk you into not thrashing the 'old guy mobile' lol ..

but seriously that thing has a nice trim on it .. a good paint job would go a looong way on that one

why the 3.73 ? just curious they do have that gear but it's kinda rare .. most have 4.10 or 3.55 ..

you COULD be our guinee pig and be the first to try a 3.08 highway gear ..

i bet the idi could push that slug plug just fine with all the bottom end torque ..

really i'm suprised nobody has swapped out to a 3.08 (that I know of anyway) i can't because i'd have to match front axle and that wouldn't be doable ..

it'd probably work well .. maybe not if you need to tow or off road idk .. but yea i think the GVOD is a bolt on deal so probably just need a rear shaft cut and you'd be good to go ..

"maybe i am just hard to please?"

sounds like it .. but most of us here are ..

thats' why were diesel people .. if we just wen't along to do what everyone does we'd go out and get a gas job ..

plus .. if we weren't strange enough as dieselers' .. we have to deal with being the not a dodge cummins guys

these motors are great once people understand how to start them (crappy glo plug setup) and they re-gear them to keep up with traffic ..

okay going off the rails

 

3.73's are common on later trucks. They were a compromise gear that was definitely best with an OD transmission. With the strong bottom end of the diesel just skip it and go to 3.55 and try to get some kind of overdrive going on. I don't know about clutchless shifts, but the ZF-5 that I drove shifted ~very nicely. As far as 3.08 gears, good luck finding them. There was an aftermarket supplier for 3.08 ring and pinion set for the sterling 10.25" axle but I don't think it has been available for many years. Member David85 on this forum had them in his truck along with an E4OD. He was able to get almost 25mpg out of that set up, and hit 20's regularly even loaded.

https://www.ford-trucks.com/forums/7...rs-thread.html