msd distributor

I had a MSD 8534 and there was no way to add a vacuum advance. Rumble is correct that it's a closed unit. Units that already have a vacuum advance can be converted to no vacuum advance but not the other way around. VTMopar if you look at those instructions you'll see it mentions the 8543 and 8544 but those are not the same distributors as Kenn has for sale.