To those out there pondering this conversion...
It is simple. I converted mine several years ago.
Have heard that the Astros van one is most popular. I rummaged through many junk yards. What I found was they appeared to all be basically the same piece. Even across auto makers. Checked Astros and Suburbans, heavy trucks from Ford, Chevy and Dodge. Differences are mounting plates and master cylinder mountings. But all main bodies I checked were exact. It appears all are produced by the same supplier.
IIRC all the push shafts that connect to your pedal extend the same distance amount. There were differences with the eye diameter.
The power brake setups don't push directly to mc from pedal like the manuals do. They utilize a sub shaft and lever setup. I retained mine and shortened the rear push shaft. Cut and welded. I read on the above referenced thread (Brads) someone cut and threaded theirs. My 74s firewall already had 6 bolt holes. Uppers for power setup lowers for manual.
I ended up using hydroboost unit from a later 90s Mustang. 3 of the 4 mounting bolt holes were in correct location already. I elongated the single hole in unit's plate to match car. Adaptor plate is only a 1/2 in. thick plate. My setup utilized the upper pattern.
Manual setup cars would use lower bolt pattern. Brads post stated push shaft (I assume originally manual setup) did not have to be cut as I did on mine.
My reason for Mustang unit was because it sits at a 90 deg rotation from the others. There is a pressure canister on them and this design (rotation) provided me more clearance for turbo piping. Plus I figured that master cylinder options would be plentiful.
Mike.
