Here is mine and my brothers/Nephews Vettes. The blue Vette is running a stock IRS with a power glide. It has a new Eton posi with a richmond ring and pinion and steel cap on left side. He runs International Axles hardened axles and outer spindles. Solid U joints. Stiff spring and shocks are a must. 11.50's is no problem at all with a IRS. Call Tom at International axle and tell him Vinny from Long Island New York recommended his products. 763-428-5020
We also run his stuff in our 63 and 67 Vettes both stick cars.
Red Vette is running a solid axle, 4 link with stock chassis.