1968 C10 3 speed to TH350

[ChevyGearHeads]

I have a '68 C10 long bed and after almost killing myself, via the 3 speed on the column, I have decided to put a 350 turbo up in there. I was wondering what size tail shaft I will need and what other modifications may be needed?
Thank you!

[R.L.]

If you already have the turbo measure it and go down to the local salvage yard and find a truck with the same length trans and pull the drive shaft for your conversion I think that's about it, if you like take your old drive shaft just to be sure u-joints work but I think pretty much anything from the 60s-the 80s will work; or have your driveshaft cut down to fit as the turbo is a longer transmission.
I'm not sure but as far as the tail shaft is concerned you may be thinking of a auto to std trans conversion where the shifter, seat clearance is a issue.

[Wrenchbender Ret]

The biggest problem on these trucks when going from a manual to auto trans. is removeing the crossmember & putting one under the trans.
I'm wondering how you "almost killed myself" with a 3 speed.

[PanelDeland]

^what he asked^

[ChevyGearHeads]

Well, the guy we bought it from threw a old warn out, untuned 2 barrel Rochester on it and trying to keep it idling was difficult and required a bit of pedal jockeying, to my dads dismay. So, as I let off the clutch (slowly), I had to let out of the gas and just as I let out of the clutch, I had to hit the gas again to keep it from stalling. So, by letting off the clutch and punching the gas, the truck took off, sending me towards the fence separating our yards. Naturally, I tried to use the clutch to stop, to no avail. Luckily the drum brakes slowed me down to a stop or I would have ended up in our neighbors jecuzzi.

[MARKDTN]

A short shaft TH350 is the same length as a 3-speed and the yoke is probably the same. But there are several obstacles. 1) crossmember. 3-sp mounts to the bellhousing, TH350 has a frame crossmember at the tailshaft. 2) Flywheel and you need a flexplate 3) starter. You will need to go to a block mounted starter on a 6-cyl.

Might be cheaper and faster to fix the carb. I'd spend my money on disc brakes.

[ChevyGearHeads]

Could you expand on the "block mount starter on a 6 cylinder" comment? Do you mean use a 6 cylinder starter ? or...? Thanks guys, it is all very appreciated!

[pritch]

Originally Posted by ChevyGearHeads

Could you expand on the "block mount starter on a 6 cylinder" comment? Do you mean use a 6 cylinder starter ? or...? Thanks guys, it is all very appreciated!

He's saying that the starter you have now is bolted to the bell housing with three bolts, going front to back. For an automatic, the starter will bolt to the block with 2 bolts going straight up. Your block will have the holes. There should be three bolt holes-most starters have the bolts on a diagonal, while some use the 2 that are straight across from each other. I believe that is a 292 thing, the straight across bolts. At least mine is.

[PanelDeland]

Don't foget that you'll need a new steering column for the auto,plus the associated linkage.

[1971_c10]

i agree with the others. the crossmember is a pain. I went from 3 on the tree to 700R4. hardest part was the crossmember on the manual. as for the auto crossmember, i did what R.L. said and went to the junk yard and got one from a donor truck (and modified it slightly for the 700R4). and I didn't change the steering column. i just tossed in a B&M floor shifter made for trucks (just has an extra mount to make the shifter sit higher).