i ran this in the z06 section and got 0 responce.

ok, i suffer from ccd, compulsive corvette disorder. had it since 1972 when i bought a 68 vert and it has gotten worse over the years. before that it was compulsive chevelle disorder. anyways, i have had my 2007 z for the last 9 years and have done nothing to it except for fluids and maintenance items but that all changed when i sent my heads to ahp for kohle and the gang to fix them for the guide/valve issues and that is when it struck again. heads/cam/exhaust/intake/etc. and also poly bushings, coilovers, brakes/rotors and some heim jointed pieces. that is all completed and now time to move to the rear area. pulled the brakes, control arms and cradle. diff and trans are tied up with some moving strapping getting ready to start de-crudding the rear end and panels.
now to the question at hand. the diff mounts seem to me a little sloppy? not firm, and i am going to replace them. i am replacing all the bushings with poly and new ball joints but am wondering about the diff mounts. factory rubber or poly to match the control arms. will poly give me a noticeable harsher ride just over the poly bushings or be more abusive on the rear end, vibration wise? pros and cons are greatly appreciated

 

Poly will give more NVH than the OE rubber mounts. I'd say if its a street car, and you're leaving the OE rubber motor mounts in, might as well stay with OE rubber trans mount...and why not freshen those motor mounts up as well? If you want to go with poly, I'd pick up a set like Hinson's for the motor and trans. But again, you'll experience more NVH with the more poly rigid mounts. It's a very subjective topic...NVH, Drone, etc....and what you're individual tolerance levels are for those types of things. No one but you knows what that is.