Have question about drive shaft in older truck.

Building a 1969 Panel truck my grandfather had, Doindgfew mods he would not approve of. Sorry Pa.

One is adding a 4L80E transmission. Drive shaft need to be shortened 4". I can have that done easy enough. I also have a 3" drive shaft out of 94 2500. Would require same cutting, moving carrier bearing some(not issue with new crossmember). Question is. Would the benefit of stronger shaft(logt bigger dia.) and stability at higher DS speed like when I get bored and wrap needle around speedometer actually be noticeable and make worth trouble. Could be me over engineering something and that never happens,LOL

Driveline experts advise and keyboard experts welcome to play too.

When a drive shaft come apart ot takes a lot of stuff with it. I had one come apart and it broke the bellhousing off the T400 and I still have a hole in the bed where it tried to come thru. I went to a 3 1/2" aluminum and haven't had a problem since.

Yea but mine is behind a nothing 454 maybe 450 hp when done and that is being hopeful

Read and understand critical shaft speed. Not worth wrecking anything over an inadequate driveshaft. Has absolutely nothing to do with horsepower, it's 100% rotational speed.

Have read. Since this shaft has already been spun fast enough for this brick to be 130 with 3spd.With overdrive might get lil more out of it but still pushing big brick threw the wind, It is little drive shaft too. If go with one out of newer truck it is larger diameter ,n0t sur how thick material is. Know that neither is designed for what it will see speed wise when I get out on open road and bored.

Critical speed is why thinking driveshaft too long for one piece.

More wondering if benefit of larger diameter is worth the moving things, cost and making parts work together. Power concern is more with me hammering it at lights.

With new frame stiffening piece that I am installing the whole shaft will be in cased with multiple hoops. More for stiffening but figured might as well add lil safety feature at same time.

This message has been edited. Last edited by: wideopen231,