I had the possibility to buy one on Rockauto. But it does not fit. The distance between the screws are less then the originals.. Will contact them but is this possible that there are two different versions?
I have an original brake booster I pulled off my '79 when I went hydroboost, probably never will re-install it(just kept it due to it being original to my Ranchero). It was working fine when removed, been on my warehouse shelf since removal. I believe it is 11" diameter/pancake style of booster. Let me know if you are interested.
If I´m lucky and Rockauto will take it back, than I would like to have yours, If not I have to check where to sell it and then I will come back to you but Yes I would like to have it. Could you contact me (Private Message) about pricing? About your Hydroboost modding: Was it hard? does standard parts fit or do you need special parts. And is it expensive?
I took a hydroboost unit from a Chevy Astro-van due to it's mounting style(easily removable mounting plate) and fabbed up my own mounting plate to match firewall brake booster stud layout. I rebuilt/resealed the HB unit, I had to cut the brake pedal input rod to reposition to Ranchero brake pedal stud, then welded it with gussets. I used Corvette master cylinder to allow brake lines to exit on fender side and due to it being 4 wheel disc MC. The Astro van HB uses a lock nut and keyway to locate mounting plate, makes for a very easy install with mounting options. It wasn't a bolt-in install, but I only have about $100 in the HB/MC combo.
I sent a PM, not sure it made it. I'd sell this one for $50 plus shipping. If you want it, I will box it up and send it for just the shipping charges. Once delivered and/or installed send me the $50, just want you to be satisfied with your purchase. Here are the pics, it's not pretty but it does work correctly-I ran a vacuum hose from intake with engine running and compressed pushrod, worked as it should or at least as best it could-my engine only makes 13" vacuum @ idle(another reason for HB switch).