Instead of trying to explain.... and without pictures or diagrams..
Open the Spicer manual here and read the instructions and look at the pictures, they're worth at least 1,000 words.
http://www.stovebolt.com/techtips/driveline/setup/index.html

I question the 3* offset for expected torque/roll of the axle. I'd set it so the angles are all happy for normal driving, which requires very little torque. Also these springs are very stiff and short, not likely to change pinion angle much even in low gear pulling stumps..
If your shop is accustomed to working on drag cars that may explain their reasoning.


Last edited by Grigg; 03/27/2016 1:41 AM. Reason: More info
•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-