hydroboost matchup

[towman1970]

i have a 1982 chevy 1-ton with hydroboost it leaks so i got one from a junkyard they are the same unit and matchup but the mounting plates are different size and on the one from the junkyard behind the plate looks to be a large nut to take off the plate i havent got down to the shop till next week can anyone tell me if the mounting plates are interchangable?

thanks

towman