It's a pun...
If you only need vacuum for heat controls a small and cheap vacuum pump will suffice. I don't have any recommendations on which one, but a number of different ones were used as original equipment on cars and trucks, some searching will turn up options and opinions.
I've put hydroboost on three different trucks now, and can't see any reason not to do it again. If you already have PS there is no good reason not to use a hydrobooster.
Grigg
