I have a 1975 long bed with a big block and c6. I had a slight driveline vibration for years running a 68.5 inch single shaft. I aquired a 2 piece shaft out of a 4 wd and that worked very well. It really comes down to what you are going to do with the truck, how much power etc. I pushed the 2 piece shaft to 11.73 and didn't break it, but I was nervous and greased the ujoints every week. Randy.this is going in a long wheel base truck and it is a short tailshaft slip yoke type. is this the right way to do it? or should i hold off and look for a different one?