i just bought an oem clutch master rebuild kit GM OEM PART 18031467 AC DELCO 18G751. i don't know if it's for the early or late style.....or if it even matters? i know they're the same bore, but what about stroke?
for future reference.....it was for the newer style master, but i was able to hone mine, turns out the seal was fine. i got moisture from a sloppy bleed job thru the firewall...