switching from th350 long tail to th350 short, help please...

[78C10BigTen]

Hey every one my 78 2wd long box currently has a bad th350 long tail, i need some help and information on how i can swap it to a th350 short tail. My first question is do the long and short tails use a different mount on the cross member or is it just the tail thats different? My next question is how or where can i get a longer drive shaft to reach the shorter tail? Has anyone been down this road? Please help me, thank you all.

 

[74 Shortbed]

All you need is a short housing and shaft, tranny will have to come all apart to swap since the tail shaft is the first part in the case, mount is on the case s nothing changes there, it's a quick and easy deal. Local driveline service can take care of the driveshaft for ya.

 

[78C10BigTen]

Thanks for your help, i shoulda clarified a little better. im not swapping tails im simply swapping the whole trans but instead of using one with a 9" tail im going to use one with a 6" tail. Im not sure how to get a longer drive shaft but its a help to kno that the mounts are the same.
My problem is it was running good one day then the next i came out to go to work and had no forward gears what so ever but reverse was spot on perfect.

 

[74 Shortbed]

Easier yet just bolt it in. Should be a driveline service in your town, or check with a machine shop some do driveshafts.

 

[CTXSquare]

Sounds stupid but what did you do as a solution? get a new driveshaft (via custom) or find one that worked? I had a trans rebuilt but didn't pay attention on what the original trans tailshft was and i am literally in the same boat.

 

[HotRodPC]

I'd keep it the intermediate 9in shaft. You know the long half tons with the 6in short shaft were 2pc driveshafts. To eliminate the need for 2pc driveshafts in the longbeds like the 69-72 year model trucks, the 9in intermediate shaft came about.

 

[Swims350]

if you can find a junkyard or another truck same length with a 3 speed on the column it's the right length and spline for a th350 short shaft.
. My dad's 84 short bed c10 had a long tail or 9 inch tail th350 in it and we put in a th350 6 inch short shaft, all bolts up perfectly, just need the driveshaft 3 inches longer. We bought one in a junkyard for it for 65 and it fit perfectly we knew the length we needed and measured, but the manual trans 3 on the tree 2wd is the same, not the sm465.

 

[GMFORLIFE]

It's easier to get the correct transmission rather than getting a custom drive shaft.
If your hell bent on using what you have take acurate measurements of your drive shaft and add the difference between the tails and order a custom driveshaft.

 

[78C10BigTen]

Sounds stupid but what did you do as a solution? get a new driveshaft (via custom) or find one that worked? I had a trans rebuilt but didn't pay attention on what the original trans tailshft was and i am literally in the same boat.

I actually just kept hunting CL till i found another 9" tail 350 and just happened to get lucky that it was good.