howdy. I've got a 4x4 '85 F150 with a 300 inline 6 and the NP435 transmission. I really like the truck, but it likes gas. I'm thinking of swapping the NP435 for one of those 4 speed overdrive transmissions that a lot of these trucks came with in the 80's. I know this is a fairly common swap, or at least a swap from the overdrive to the 'granny gear' transmission is pretty common, so hopefully some folks here will have done it before. What's the brand and model number of the 4 speed overdrives that these mid 80's ford trucks came with? Also, is this a pretty straightforeward bolt-in swap, or are there issues with pilot bearings, clutches, transfer cases, driveshafts, transmission mounts, or other stuff? Thanks for any advice.

 

it should work.i did the same thing for a guy in kentucky who had an '86 ford f150.worked fine without the need to change mounts,bearings or any other related parts.it should drop it without much effort.you might want to use a little grease on the sides where the mounts are so it won't stick too much.

 

Thanks for the advice... one more question, though. Was there a difference in length? Just wondering if I'll need to get different driveshafts or have mine modified.

Anybody else done a similar swap? I'm interested in hearing any war stories regarding transmission swaps in these trucks either from the 'granny gear' to the overdrive or vice versa. I've heard there are issues with the speedometer cable? or is it just the gear?

 

Some advice, Stay FAR FAR away from that 4sd od pos tranny that ford used in the 80's if plan on doing and hard driving. They are a weak tranny that was produced (ironically based off on of the strongest 4sp's ford used, the toploader 4sp used in the 60's and early -mid 70's, and is the tranny i swaped in my flareside to get rid of the same 4sp od you are talking) to get better milage out of the I-6 and 302's in 2wd 1/2 ton trucks.

However if you have your heart set on doing this swap its a straight forward swap, i can't remember if you need a d-shaft, but it wouldn't hurt to grab it from the truck you source the tranny from if its the same wheelbase.

If you have you heart set on an od tranny i would get a ZF 5sp from 87 and newer 3/4-1 ton trucks, as strong as your NV-435, but the first gear is a little high, but you have 5 gears with od.

 

One of my trucks has the 4 spd od in it and it has been beaten just about as hard as any truck maybe harder and i havent had any problems with it. The only problem you will have with putting the tranny in is the tranny mount. The whole crossmember is different so if you get the tranny out of another truck be sure to take the crossmember also.

 

Thanks for all the advice. From what people have told me, this 4 spd overdrive works fine as long as you don't overload the truck. I've had it almost 5 years and have never hauled more than a ton in it, and then only twice.

Anybody else deal with this swap? I probably can't afford the 5 speed, but so far I think the 4 spd overdrive should be pretty much a bolt-in except for the crossmember.

 

Be sure you give the tranny a good once over, and if possible the ones with the external shift linkage have a better shifter (you can get a hurst shift for this type), as the aluminum tops (shifter thingy, when you see it you will know what i mean) on the trannies tend to break.

Oh, whatever truck you get this tranny out of be sure to get the center floor plan as well, as the hole for the od tranny is further back towards the seat.

 

I haven't had any problems with my 83 4OD and I've loaded some real heavy loads and even pulled a 22' travel trailer once.
Correction: One problem....the truck always avoids gas stations!

 

the fuel effencency you state seems good.just fine tune your fuel input system a little to extend your range.it will be money in your pocket.

 

the "od" users r screaming praises of their great gas mileage. I must know what your gettin. and what setup u have. tires rear end and motor.

 

I get about 10 mpg in town with my od trans and about 20 mpg on the highway over 65-85 mph. Thats in a bone stock 85 300 with 3.08 rear gears and 235/75 tires. If you live in an area with any hills i would stay away from an early 80's OD unless you have 3.73 gears or lower.
I have been concidering a gear chane or tranny change any opinions on the mazda tranny?

 

the mazda trannies are just as bad, the 1st and reverse gearing just plain sucks (even with 4.10's, we have a 93 super cab 4wd/302 with this tranny, and it broke the other day too). The ZF 5 speeds out of the 3/4-1 ton trucks are nearly bullet proof, but then again the 1st and reverse gears aren't that great in those either (or at least in the truck i drove that had it)

 

I have a 4 speed manual (with overdrive) as well. My truck is stock with a 3.00 rear, and 235/75 R15 tires. My fuel injected 302 gets around 15-16 miles per gallon in mostly city driving. For highway driving it goes up to around 18 or so. This is a 2 wheel drive truck.

The only thing that sucks with this tranny is the first gear is kinda high. I do sometimes wish I had a granny low, but oh well.

-Matt

 

im running bone stock motor w/3.55 rearend and 32x11.50's. i rarely drive on the highway for any long distance.my gas mileage stays around 13.5 per gallon.w/ the np-435 ( granny low first)now with 33's i only got around 11 per gallon so i'm more interested in wiching tires to a smaller size than swapping a tranny.if any one has a similar setup and dose change the tranny i would like to hear from u.

 

Mustang70, you seem to know a bit about the 5spd trannys. Can you tell me what the gear ratio is on the 5sp compared to the 4sp od. I have a 81 f100 with the 4sp od, and I found a 5sp from a late 80's (I think it was a 1990) f250. Do you know if I would have to do alot of modifications or will it drop in.

Iskerbibel, I have not had my truck very long and the 4spd od trans has given me no trouble except that 3rd gear is a little bit of a stretch to reach, and 4th and 2nd puts the shifter over the seat (that prevents me from getting an armrest). I am the 3rd owner of this truck, the original owner got it as a work truck, and the 2nd owner told me he bought it to tow his cars from springfield Illinois to Elgin Illinois ( near the northern border ). He towed 6 cars, and they were all older cars that weighd atleast 3,500 lbs each, one I saw was about 5,000 (that is about 500 lbs more than the truck weighs). I don't know what the rearend is on my truck, all I know is that it is a 9 inch.
And the engine that was in the truck when he did the towing was the 255 v8 (not very well known as far as strength) but the engine did pretty good considering it was a lame attempt at a fuel efficient 302. But sadly he let the engine run low on oil for too long and it developed a rod knock.

I like my od tranny. The only reason I may switch is because I am a little new at driving a manual rear wheel drive, and if the 5spd has a lower gear, it could help on the icy hills. Good luck with your swap ,and watch out for thoes Crossmember bolts.