Upgrade to aluminum/plastic master cylinder

[Pyrotechnic]

Thanks Keith. I looked up part numbers for boosters and there are different part numbers for 1973-1980 and 1981+ and like you say I can see in the pictures where the hole in the later models are larger. Too bad, the booster I'm running is pretty new so it'll have to stay a long with the cast iron master cylinder. Guess I'll just order a new lid and gasket and hope it seals.