Thanks for all your input guys! I REALLY appreciate it.
Started to quote individuals but most suggest cab bushings. So...
This is the cab bushing set I installed:
http://www.summitracing.com/parts/ENS-3-4108G/
Instructions list a 0.1" taller sleeve in the rear cab position.
Poly bushing thicknesses as installed using dial calipers.
Core Support - 0.750
Front cab - 1.01
Rear cab - 0.875
I have the taller (by 1/8") bushing in the front cab position. Winner?
More pix with measuring tape: