TH350 driveshaft options

[barry1982]

Hmmm.... I have been down this road before. Have seen three different length TH350 driveshafts. Full size cars had a 12" tail, early 80s light duty pickups had a 9" tail (with one piece drive shaft) . Camaro/Nova's and heavy duty pickups had the 6" tail. To keep costs down you have a couple options. Go to the wrecker, and pull the shafts/steady bearing assembly from a heavy duty truck. I can't quite recall, but you also may need the support for the steady bearing. Option two is a bit "sketchy" ..... but I have successfully done it. I happen to have quite a few parts trucks, and am a fairly good welder. I cut my original shaft a few inches in from the rear u-joint with a precise tubing cutter.
Cut another driveshaft three inches longer. I butted up the new section, and clamped it tightly between two angle irons to hold it true and tack welded with my Miller Mig machine. After tacking, removed the angle irons/clamps and completed welding. Was going to take it to a machine shop for balancing, but for the heck of it tried it on the truck. Got lucky, and it worked smooth as silk..... I ran the truck quite a few years without any issues. Like I said though, option one is better. There is probably a reason the GM Engineers called for the two piece shafts with the 6" tail trannys.