I made an assortment of thickness of spacers, both steel and billet aluminum. (Do not buy cheap cast aluminum spacers, they're garbage). I used 3/8" on the eleven second car, 1/2" billet I made for the nine second car, and I have 1 1/2" billet that I bought, on the eight second car, that I modified to suit me. All my cars have at least 3" studs, the eight second car has 4".
Perfect I I feel more comfortable knowing your using those size spacers on a rack driven car. My car will be mostly if not all street driven.. 1/2 spacer is likely max I’ll need. I appreciate your experience sharing, thanks!
