Originally Posted by Zo39
I have done alot of research on this and the only article found was Jay Leno's 66 gold Toronado. He put a c5 suspension and drivetrain in the Olds. It stated that he extended the torque tube but no other imformation. I am a tool and die maker- machinist by trade with custom body work as my hobby. The stock prop shaft is 2" aluminum tube .090 wall. I plan on using 3" alum tube .125 wall sleeved over the stock ends 7.5" longer than stock. The torque tube will be cut 3" in front of the trans housing so the shifter to seat and dash stays stock. I will use a 6061 alum 5.5" sleeve over the 5" torque tube to extend it. Any suggesions or ideas are appreciated. Thanks Tln Z039
Sounds like you have a lock on the problem, especially the tube.
Just as another resource to consider, The Driveshaft Shop has mucho experience and expertise in after-market propellor shafts for C5s (and C6s as well). They, in fact, offer a 3" propellor shaft for C5s and may be able to just make one for you in the correct length to begin with. "Whipping" is a potential issue that should be considered when lengthening a shaft, but may be greatly mitigated/eliminated by use of the greater wall thickness and diameter. Of course balancing is critical as well.
Which coupler design are you going to use? Personally I have had success with Prothane's "Six-Shooters" but also DSS makes a version of their own as well, that receives high marks for strength/durability. Protection from any exhaust heat is far more imporant for polys, but that's easily remedied.