My truck needs a new transmission. I'm planning to swap it out once the weather gets warmer, but before that happens, I need to find a replacement. Specifically, I'm looking for a C6 to fit in my 1976 F-250 (2WD), which has a 390 FE engine.
The problem, of course, is that the odds of me finding a 1976 2WD F-250 donor and a C6 in good condition are exceedingly slim. And I'm pretty sure that not all C6s will bolt up to my 390 and my driveshaft. So my question to you all is, which C6s will drop right into my truck?
As I understand, the variables involved are:
- The bolt pattern (I think all FE blocks have the same bolt pattern?)
- The length (and tail housing)
- The input shaft dimensions and tooth count
- The starter configuration and ring
And that's about it, as far as I know. There are internal changes to the C6 (e.g., the fluid was changed in 1976 from high-friction to standard ATF) but as long as they're internal, I don't really care.
Will any 2WD C6 mounted to an FE engine work for me?
The 352/360/390/427/428 FE engines are going to be the best bet for a transmission swap.
C-6 transmissions that are bolted to Windsor, Cleveland, or M Family which include 302/351/400/460 have to be machined to fit the FE series.
The FE series motors were replaced in 1977 while the C-6 transmission remained in production into the early 1990's.
Hope that answers more questions than it introduced.
Fantastic--that's exactly what I was looking for. I sortof figured the C6s fitted to 351s and 400s wouldn't fit, which is too bad since there are a ton of those available in late-1970s Broncos and F-series trucks.
Thanks mondo!
Oh, and any idea on the tail housing length?
Tailhousing length?
If you find a 4wd model C-6 chances are it had a divorced transfer case. The reason for the divorced case was a simple solution without altering current transmissions to allow 4wd. The transfer case is not bolted to the transmission rather a stub shaft is between the tranny and t-case.
The downfall for the cheap solution was bad driveline angles on SWB trucks.
Oh, interesting. There are, as I understand it, differences in the oil pan (and possibly filter/pickup?) on the 4WD models, so I'll likely just avoid those altogether.
I had heard that not all tail cones on C6s were the same length. But who knows—I'll likely just ask any sellers to measure the case length to confirm it's the same size as mine.
Thanks, dude!
--D
Phil really covered it. If you start finding them, I wouldn't worry to much about the wrong tailshaft length if you find a good deal, as driveshafts are cheap. You can have yours fitted at a pretty reasonable cost by reusing the existing yoke.
True—that's a good point. And even better, I could possibly even swap the tails on the two transmissions.
If at all possible, I want to avoid having the truck out of commission for longer than a day. It's difficult having a sloped driveway, a 216" long truck, and a 180" deep garage.
216" long, and a 180" deep?
Are you talking about sex toys or transmissions?
Haha! Triple entendre!