Help with trannys? 🤔

[HoneyBeeMan68]

So I was reading cjoenny89 new clutch not disengage and it made me think about what I have. So I have a 68 long stepside which should have a 327 3 on the tree in it . But the 1& 2 owners blue up the motors that they put in. The 2 motor was a 305 with the tranny all cast iron gm 163952645 a190 e10 tail 3860042 gm 32 main body gm26 3926647 e600 ( I think Saginaw 343) and was given a free tranny marked cast iron gm122952647 d23 f64 main body gm338835 #2 tail 6261884 gm4 . I think from pictures it’s a Saginaw 456 . Sorry for the long info, but I have a blueprint 355 and some friends say the 3 speed will not handle the motor so before I buy my pressure plate I was hoping to get more insight for you guys! The picutes show different tail housing on them. My question is a: can I use what I have or will I need to go with a 4 on the floor?

[HoneyBeeMan68]

Here are the pictures of mine and the reference page I’am looking at. The top left one is the one that was in the truck when i got it hooked up to a 305.

[Accelo]

The pressure plate for the 3 speed and the 4 speed will likely be the same. Get the clutch you want and go driving. If you transmission blows you have lost very little. Just get the 4 speed and move on.
The transmission holding up has as much to do with the tire width and driving habits as anything. It may last longer than you believed possible it you don't drive it like you were 16.

[special-K]

Not crazy high HP, but GM put the Saginaw 3spd behind the big block. I've had two short beds with that set-up. The '68 396/3spd was one of a matching pair ordered by brothers for street & strip. Didn't want automatic/couldn't get car-type 4spd. I was surprised they never swapped in a 4spd. So easy to do. That's what I did with both trucks.

GM put the 3spds in K/20s. That's an application that can demand a lot from a drivetrain.

As said, it's all in how you drive

[ghackett1]

FWIW:
I put a 355 in my truck that had a 307/3speed in it. I switched to a muncie 4 speed, used a car 621 bellhousing, new clutch/pressure plate and it fit as good as the 3 speed Saginaw did with the old motor. Easy swap. I also installed an automatic tranny support to catch the rear of the Muncie so it wasn’t hanging off the bellhousing.

[Yamariv]

Originally Posted by special-K

Not crazy high HP, but GM put the Saginaw 3spd behind the big block. I've had two short beds with that set-up. The '68 396/3spd was one of a matching pair ordered by brothers for street & strip. Didn't want automatic/couldn't get car-type 4spd. I was surprised they never swapped in a 4spd. So easy to do. That's what I did with both trucks.

GM put the 3spds in K/20s. That's an application that can demand a lot from a drivetrain.

As said, it's all in how you drive

Are you sure they put a 3 speed Saginaw and not the HD 3 speed? My understanding is that there was an HD 3 OTT tranny specifically for a big block as the Saginaw wasn't rated for it.

[HoneyBeeMan68]

thanks, I'll run what I have then.