Thanks, Canoe. It's a 1986 Eagle Limited with the 4.2 L engine and automatic transmission, soon to be 4.0 L stroker. I don't know if this is the stock booster or not. The engine is out of the car, so we had lots of room to work, except where the lower left section of the booster was hitting the inner fender. I don't believe there's a direct correlation between booster diameter and the force the booster creates. If I can't find a suitable smaller booster, I'll probably massage that section of the inner fender in by about 1/4".