49TT - I couldn't find anything listing a Bendix "547550" hydrovac. Sounds like a replacement, but I also couldn't find any reference to a repair kit for the same numbered unit. You indicated you found sources for kits, but are those specifically for the Bendix 547550, or were they kits for the 374000?
After a little deeper diving through multiple Chevrolet Master Parts books, I found later books show a Bendix 378802 (GM# 3761237) listed to replace the Bendix 374000 (GM# 2208488) in a 1962 Chevrolet Master Parts Book. Both the 1957 and earlier books and the 1962 book listed these as fitting ALL Utility Trucks (1-1/2 & 2 ton), so I think either one works for your application.
With that in mind, a little further web surfing found you can get a remanufactured
Bendix 374000 from Powerbrake-Drivetrain for about $795, which includes a $200 refundable core charge. Your choice on whch way you decide to proceed, but this is another option to consider.
Looking forward to hearing which way you go.
BTW - Posting some pictures of your truck and the items being discussed can often help folks help you in solving some of these hard to resolve things. Plus we love to see what your working on!
