c20 two piece driveline shorten or go 1 piece?

[Greubin]

I'm prepping for a 700r4 install in my '71 c20. The driveline needs to be shortened, so I'm wondering if I should have the original forward half shortened or opt for a 1 piece driveline. If I shorten original, obviously the forward half would be shortened. SHould I measure from the back of trans to the driveline bearing support? If I go with a 1 piece then I'd measure from end of trans to the third member yoke.

Recommendations?

[70GMCer]

I'm going to have to be doing mine in the near future. I haven't did any measuring yet. I've seen where the 700r4 is 3" longer than a 350 turbo. So, I'm thinking that 3" cut off the front drive shaft would do it....

[Steelawork'n]

I hear both ways. You will probably have to go to a bigger diameter if you go to a one piece.

[Karl Hoh]

Most driveshaft builders work off a "tip to tip" measurement, and do their own math for yokes etc. I've heard that max. length is 72 inches for any one shaft. U-joint angles are the most important thing.

[Longhorn Man]

72 inches is the most for many places. If they work with alluminum, then they may go longer.
It's a bad idea to go longer than 6 ft with steel, esp in an overdrive aplication becouse the shaft runs faster than the crank/flywheel making the slightest vibe exadurated. That's what our local drive shaft shops say anyways.
Just get it trimmed down, have a quality carrier bearing installed, and good u-joints.

[Greubin]

Thanks for all the replies...I'll have it trimmed down, sounds like the best route.