Mocking up my t56 so I can get the tunnel built. My question is, what's the best way to get an accurate measurement with the weight off the front end? Should I just zero the angle finder to the frame? Thanks for the help.
I would think you would need the car sitting at ride height. The driveshaft isn't going to be pointed up no matter what if that helps. http://www.buickperformanceclub.com/Pinion.htm
You really just need the rear suspension supporting the weight of the car, and moderately level. If the front is raised, just raise the back enough to stick on jack stands and measure. I use the Tremec app on my phone.
When I did mine, I put the rear axle on jack stands so it's at ride height and then raised the front till the frame was at 0 degrees. I adjusted my trans with a jack until the driveline angle was 3 degrees down and built my crossmember that way. Next is building the floor.