I just picked up a 78 f350 with a 351m and a 4speed, I was wondering if the 4 speed will work with my 74 highboy. I have a 67 352 in it, I know I am gonna have to change the bellhousing and the flywheel but I wasnt sure if the bolts on the tranny itself would line up with a FE bellhousing, also I was wondering if the yoke for the driveshaft would have to be changed as well? Anyhow if anyone has any advice I would appreciate it. Thanks, Jack

 

the trans from an fe will not bolt up to a 335 series (351m-400) block. the trans will bolt to a 385 series(429-460 ) block. so 335 series to 385 series will interchange. fe to 335 series or 385 series no interchange.

 

You're switching from an auto to a manual then? 99% sure the 4 spd trans from the 78 will bolt to the FE bellhousing.

How similar is the configuration of the two trucks? 2wd vs. 4wd, two piece driveshaft vs. one. The closer the configurations are, the easier the conversion is. Makes a difference on the yokes, whether it's fixed or a slip yoke. That's a big difference, but not insurmountable.

Fords being Fords, chances are the yoke and U-joints are different. But those are easy changes.

 

now im confused. are the trans in both trucks standards,or is the one truck an automatic? if they are both np 435 4speeds , ithink they should interchange with the right flywheel,and bellhousings. as peganit2 said, the closer the similarities of the 2 trucks the better the chances are they will swap. im assuming the 78 is a 2wd. that may bring up some swap issues too. nothing that can't be over come though.

 

if your looking at just using the tranny, then yes, every one i've seen is the same. you need the 2wd tailshaft, which you have, and you will need a bellhousing and flywheel from an fe, which i dont know what trans you have in the truck now. if you have a stick, you will only need the flywheel.

 

Oh, sorry I guess I should have said, the transmission in the 74 highboy is a c6 auto, and yes, the 78 f350 is 2wd and that is the one I am taking the tranny from. I was told that a tranny from a 2wd truck should work in my highboy due to the highboy being divorced mount. I was just curious about the driveshaft yokes being different splines or something like that. But basically, I am trying to bolt a FE bell housing to a 4 speed that had a 351m bell housing on it. Thanks for all the responses, I would have gotten back with this info earlier but for some reason the forum only e mailed me one notification, then I logged on and found that I had several responses. ------Jack

 

im thinking if you have an fe bell housing, flywheel clutch,etc,it should go on.if im missing anything someone wll correct me.

 

Well that is good news, I just picked up this parts truck recently and I was so happy to see that it was a 4 speed, the C6 auto is the only thing I am not too hot about with my 74 highboy, especially now that it doesnt want to move when its cold lol. I have a FE flywheel and clutch so thats no biggie, now I just have to find a bell housing.---------Jack

 

Big difference COULD BE the yoke, but it's very easy to tell the difference. The 2WD trans very well could have a slip yoke and the 4WD trans SHOULD have a fixed yoke, bolted to the transmission output shaft. Obviously, the slip yoke can come out of the trans, and the fixed yoke will not. That difference would be a PITA. I would stop the conversion if I found out they are different, unless I understood the discouragement in the difficulty in making it work. Driveshaft and or output shaft changes. BIG changes.

I'll post pics of the difference soon.

Here are the pics;


Here's the fixed yoke. Note the big nut in the center of the yoke and a plain seal. This is my highboy with a C6.


Here's the slip yoke. Notice no nut and a bellows type seal. This is a 5 spd from a Ranger.

Changing one way or another is a PITA.

 

Yep, you were right, that is the way it is on my truck. I wonder why they did that, you would think a slip yoke would be able to hold the torque. Maybee I could change the yoke on the 4wd driveshaft to a slip yoke form the 2wd shaft?

 

Somethings gotta give. But you CAN'T have both a slip style driveshaft AND a slip yoke.

You checked the yoke on the 4 spd?

 

Yea, I was thinking of looking at the 2wd tranny just to see if the yoke is different, after all the truck is a f350 so maybee they used the same type of yoke as the highboy has, I hope so, but I won't know till I look.

 

Should be the same.

 

Jack, you're gettin' yourself into A LOT of work. You have the pedal and assembly from the f350, but because you're going from one engine family to another, you'll still need FE: flywheel, bellhousing, clutch(new), pressure plate(new), throwout arm, throwout bearing(new), pilot bearing(new), manual transmission mount(new), yoke and drive line to TC.

No need for slip yoke from trans to TC as they don't move relative to one another. Slip yoke is necessary from TC to diffs.

Soon someone with a highboy will be along to clear up the yoke to TC issue.

Frankly, I'd hunt up another 4x4 with a FE manual trans for a donor for all of the right parts. But, maybe you have a PnP close by to get those parts. I've converted an auto to manual the hard way and if I ever do it again I'll get a donor of the same configuration. That way there's parts AND a template for reference. Just my experience, apparently I haven't gotten over the trama of doing it the hard way.

 

My Highboy has a slip DRIVESHAFT between the transmission and transfer case. They DO move relative to each other. Not as much as the rear end to the trans for sure but there is relative motion.



My mistake. Not a slip shaft. I wouldn't take this joint out of the drivetrain myself though.