It's been ages since I have seen anything on the GM 12" brake conversion so I'll have to ask this, wouldn't the '70-'81 F-body & '73-'77 A-body spindles also work since they use the same (as almost all '67-'77 GM cars) D52 brakes?
I don't think they will fit without spacers and the LS1 brakes with spacers is super sketch. The broken stud on my LS1 brake picture was done without spacers. Wheel adapters might stabilize things, but the LS1 brakes already space the wheel out almost 3/8", so a narrow front tire is required if a spacer is used.
Ok I found my proof! Lol.
That is a t type vector on ls1 caliper setup, no spacer. I called BS that it would fit too but a local g body guy had ls1 brakes on his MCSS with the stock wheels and he said it cleared with minimal grinding on the fins. He claimed most any 15" aluminum wheel would clear and I tried my t type and by God he was right.
The tire would only turn 20 degrees before the slight run-out in the wheel started rubbing but a 2 minute shot with a flap wheel would clear.
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