I agree , try the vacuum can first, you dont have to buy a new one, just rob one from an old lincoln or big merc. Your trans case will be stamped or cast with a casting number. All you need to be concerned with is the first 2 digits (example = C9__) where C= a product from the 60's, and 9= the year, hence 1969. If it was biult in the 70's it will start with a "D". D6 = 1976. Good luck.