Correct TH400?

[Olive1970]

Looking to put my truck back to factory at some point. It is a 77 C10, originally had a 454/400, is a big 10, LWB with one-piece driveshaft. My question is with all the variations of TH400 transmissions, which would be the correct one for the truck? Having trouble figuring it out with all the different tailshafts, bolt on or fixed yoke, or just a splined output shaft?

Thanks!

[kwmech]

Short shaft slip yoke would be my guess

[sweetk30]

this truck was used as a donor body for another . but here is a pic of its th400 . c10 long bed truck .

[porpaintt]

Olive,I have a 78 454 and 400 out of a c10,I will see if I can get a pict tomorrow and sent it to you.

[Olive1970]

Originally Posted by sweetk30

this truck was used as a donor body for another . but here is a pic of its th400 . c10 long bed truck .

Hard to tell from picture, but is this a one piece driveshaft also? Thank you!

[Olive1970]

Originally Posted by porpaintt

Olive,I have a 78 454 and 400 out of a c10,I will see if I can get a pict tomorrow and sent it to you.

I really appreciate that!

[sweetk30]

cant recall 100% if 1 piece drive shaft . to many years ago .

but looking at the crossmember behind it i think that was a carrier bearing riveted to it for the shaft if i had to guess .

problem is once you get so long on a drive shaft it will wobble and never balance out for highway speed . so this is why there is multi section shafts . if i recall its around 65" in length or so is the max .

[Fuelster]

That might be a T375 in that frame. I have a 87 parts truck 2wd it has same tail shaft but it is a 375 not a 400. It has same yoke as t350. This one looks the same size.

[porpaintt]

Hear is the picture olive,it came out of a 78 c10 1 piece drive shaft,8 ft bed.

[sweetk30]

Originally Posted by Fuelster

That might be a T375 in that frame. I have a 87 parts truck 2wd it has same tail shaft but it is a 375 not a 400. It has same yoke as t350. This one looks the same size.

th375 is light duty guts th400 with 27 spline tail shaft .

at this point he should pick whats best for his needs and have a good quality drive shaft made and run it i think .

[Olive1970]

Originally Posted by porpaintt

Hear is the picture olive,it came out of a 78 c10 1 piece drive shaft,8 ft bed.

Thank you again! I suppose it wouldn't matter too much if there was a bolt on or slip on yoke if this is the style it had?

[Olive1970]

Originally Posted by sweetk30

th375 is light duty guts th400 with 27 spline tail shaft .

at this point he should pick whats best for his needs and have a good quality drive shaft made and run it i think .

You are probably right about the driveshaft, I am trying to make this less painful by not having to do any driveshaft tube modification. But, it may come down to that if I used a short shaft slip yoke TH400. Would have been a lot better off if someone didn't swap the engine and trans in mine.

[porpaintt]

Olive,that is a bolt on yoke,and I just sold a 90 1ton diesel that had a 375 in it with a slip on yoke,but that was because the 4 door 1 tons were winding down,and they used whatever was on the shelf to get rid of them

[cadillac_al]

I wonder when they went to the one piece driveshaft? I had several 2 piece drive shafts on lwb trucks. I figured they used long tailshaft trannys with one piece driveshafts. I'm pretty sure my 77 lwb has a one piece with a short shaft th350 though. Hard to figure the logic of it and my memory is fading. I thought the th375 was discontinued in the late 70's. The pics sweet K30 posted look like what I would expect from GM; long tailshaft with a one piece shaft.

[porpaintt]

The 90 one ton had a two piece shaft in it.
I will have to ask my Grandson about that 78 if he remembers if it had a two piece in it,if it did I should still have the shaft.

[Desert1957]

My 87 heavy half ton long bed has a two piece shaft with a Turbo 400 (375).