I just picked up my 1979 F250, 300 I 6, 4x4 today and I have a few questions for yall. First, the bed is pretty much shot, needs both new bedsides, and the floor of the bed is done for. I can order bedsides and a floor aftermarket for like $1,000 shipped but would I be better off price wise to just try to find a decent one locally and take good parts off of each to make one good bed? By shot I mean the wheel ariches are rusting out where someone already welded in a small aftermarket panel And the corners unDer the taillights are gone as well. It's an 8 foot bed so I'm assuming I couldn't get away with a 6 foot bed if I found one locally because of the frame right? Or would it be possible to take a random 8 foot bed and cut the floor out and use that from a local junkyard With new bed sides to save money? My welding is a well worked skill so that's not an issue, just wanted input.
My other question is, I'm not too good at driving standard tranny, with the stock 4 speed with granny gear the truck is barely reaching highway speeds (50 mph tops) and my 4 speed is making a goofy noise, Ive been looking these up for awhile and I know most people swap their c6 for manual, but could I do the opposite and put a c6 in and would it make the top speed a bit higher? What would be required to swap the tranny if it's possible? most of the c6 tranny I've found say they came off of 460 or 351, so does that mean the c6 wouldnt work with the 300 inline 6?
Thanks yall, and sorry about the long post, I'm just curious and sure I'll have more questions

 

First off, welcome to FTE!

The 300 is a tough motor and one of the best but not so worthy of today's highway speeds with a 4 speed and your likely low rear end gearing.. An automatic will help but again with super low gears it will not make much of a difference.. If you will post up your vin someone here can decipher it for you..

Being geared right will get you sailing at 70mph no problem

I will say that you should send that bed "block of swiss cheese" to the scrapyard and find you another one.. Even if it isnt quite local you should be able to find one rust free for under 500$.. Got one at a u pull it for 180 bucks..

The C6 with a small bell housing will be hard to find, hence most of them come behind a 351m 460 ect... Don't be fooled by the smaller C4, built right it is a tough sob!

Good luck

 

As far as the bed is concerned, I understand that you can take a Bulldog bed and reskin it with Dent quarterskins and redrill the mounting holes

 

you more than likely have a 4:10 gear ratio which means no matter what transmission you have your speed wont change all that much. 4:10's are low gears for working. what you need are high gears like a 3:55 which is a highway gear. yu can run a larger tire like a 33" which will get you up to 60-70 mph but your rps. will also be up there giving you some lousy gas milage. i have a 78 f250 4x4 with 4:10's and ran 33's. rpms at 70 were about 3grand.

 

So a c4 or a c6 with a small bell housing will work but they won't get me up to highway speeds without changing the gearing. The rpms are screaming at 50 in 4th as it is. How difficult would it be to put a c4 or c6 tranny in? What all would need done? Different drive shaft? Obviously linkage and a new auto steering column. What do you mean by a "bulldog" bed?

 

you would need a 4 wheel drive transmission with all the proper linkage, drive shafts may need to be lengthened ( front ) and shortened ( rear ) new steering column unless you do a custom floor shifter. or you can put bigger tires on it and get up to speed that way.

 

I found a guy a few hours away that said he has a small block c6 off of a 302 and the drive shafts for it to mount up, what would the difference be with a 4wd tranny and 2wd? Sorry if these questions sound dumb
how difficult would it be to fabricate linkage to work with the existing floor shifter? Thanks

 

If you have a 4wd truck you need a 4 wheel drive transmission plain and simple..if he is offering a small block c6 with the driveshafts its a good deal..(long as the transmission operates correctly..)

Ask him for the length of the rear driveshaft to see if it will match yours..

Don't forget it will not make a difference unless you change the gears in the axle

The only dumb question is the one unasked..

 

the automatic transmission will most likely be a bit longer than the standard transmission but dont quote me. a 4x4 truck needs a 4x4 transmission.

 

Your cruising rpm will be the same with your manual trans or a c6. They both have a final gear ratio of 1:1. In order to lower the cruising rpm you either need an overdrive transmission or numerically lower gears in the axles.

 

How can I tell if it's a 4x4 tranny?? I think I'll do the gears and see if I dig the standard tranny but I've heard nothin but good things about the c6 so Id probably do that as well.

 

I agree, change the gear ratio and it will tame those rpms a lot!

A 4x4 transmission will have a transfer case bolted to the end of it btw

 

Found a bed that needs less work than mine. It's off of a "79 highboy". this will fit right? I thought I read somewhere that the frame rails are different on the highboys
Thanks

 

I have read the same. That the highboys have a slightly 'narrower' frame. But I think they also said that highboys went up to 77'. I know user HIOSilver is pretty accurate. IM sure hell probally correct me lol


This is something for me to think about. My 78 150 is the same 300ci with a 4 speed. post what you decide to do and how it works out please.

 

Can you describe the noise the transmission is making? Are you sure it is the transmission? The 300 isn't a highway speedster but should do at least 60 MPH without fuss even with 4.10's.

A few easy things to check. 1) make sure is in 2 wd 2) make sure front hubs are unlocked 3) lube is full and decent looking in the front and rear differential, transmission and transfer case. 4) go underneath and inspect driveshaft universal joints by twisting the shaft by hand and checking for any slop in the U joints.

The front and rear differential and transmission take regular 80w-90 gear lube. Probably the transfer case as well depending on type.

You may even get to like that granny gear NP235! It does not slip like an automatic so highway revs are a bit lower. Takes less power also giving a bit better mileage.