I found this somewhere on this site: NAPA 10-1371 master cylinder. It's for a '74 Corvette with non-assisted brakes, IIRC.
Mine, modified for dual-circuit operation and combined with E-350 wheel cylinders, works great.
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Another view. Do you need a throttle spring? I think I have a few. But if you have to order other stuff, you may as well get it all from them.
http://i1067.photobucket.com/albums/...psztjbatpo.jpg
Tried to edit the above, didn't work: You'll need to run a new brake line from the rear port on the MC to the brake line going to the rear of the truck, run a line from the front port to the junction block on the frame, and plug the now-unused port on the junction block. All in (MC, 2 brake hard lines, 2 brake line reducers for the MC, a coupler for the new rear brake circuit, and a threaded brass plug) I think maybe $75 covered it.
93 E-350 with single rear wheels.
http://www.m715zone.com/vb/showthread.php?t=28183
Brute4c posted some part numbers farther down in that thread.
Get you a cutter drill bit for your Dremel or small drill to hog those mounting holes out. And it's worth the trouble to take the backing plates off to do the swap... it's a real hassle with the backing plates mounted on the truck.
Thanks Von-- that was going to be a chore to remember.
I'll add to his advice on the mounting hole modification: Unless you have a coffee can full of Dremel stones you want to expend in this operation, go get a large size chainsaw file (7/32 IIRC), cut it in half, and use it in a drill to work on those holes. This worked MUCH faster than any other method for us.
So I've started the brake overhaul. Changing out the master cylinder was a piece of cake but these brake drums... you guys weren't kidding when you said the drum locating screws are a PITA! The first one lulled me into a false sense of security by coming out easily but the other two on the first brake had to be drilled out. I had tried everything else. On the plus side, the brake hardware looks pretty new. At least the PO seems to have kept up on some of the maintenance. I'll keep working on these brakes but I was only able to get one done in ~ 3.5 hours...
http://i1215.photobucket.com/albums/...psworewd0b.jpg
A quick question for you guys, Does anyone know the specs for the drum retaining screws? I can't find anything despite my best efforts. The best guess that I have is that they're 3/8"-16 thread and are 3/4" in overall length. Is this correct? I'm also planning on switching to the hex head. Thanks for the help.