In preperation of rebuilding the rear wheel cylinders on my 67, I got the 15/16" rebuild kit, which is what the catalogue shows for 64-69. To my surprise the wheel cylinders are Delco Moraine 5464 079 7/8" bore. The rear end did not look as if had been apart. Any chance this could have come from the factory, or do you think both cylinders were replaced in prior years?

Anyone know what these wheel cylinders went to? Thanks

Not sure about Chevelle-land, but for Camaro's, GM used 7/8" rear drum cylinders up through about 76, then switched to the larger 15/16" cylinders. The 76-81 camaro rear wheel cylinders should bolt right up to any earlier car w/ 9.5" drums. Note that the larger wheel cylinders will mess with brake bias a bit and shift it rearward...

I have a 77 Camaro that has a different rear end in it. I bought new rear wheel cylinders since the old ones were leaking and the pin that goes in the cylinder does not fit. The number is Milehi's post is what is on the cylinder. This is the only reference I found to it on the net. I have since discovered what you stated about the different year cylinders and I am thinking I have a 75 or earlier rear end in the car.

I was correct. Those are a 67-75 Camaro/firebird wheel cylinder.

I just went through this fun for my 66 Malibu.

I ended up getting 4 sets of rear wheel cylinders before I got the right ones. I measured one set and my ruler said 15/16th but the Advance Auto guy swore they were 7/8. I ordered the wrong ones from Ground Up, and had to return them, my fault. They do stock the right ones, but I got to NAPA first, and he had the right ones in stock.

My problem was that two of the three had external rubber boots and would not fit in the bracket on the backing plate. One set had too large a round index area to fit the backing plate.

I did not measure the bore size on the ones I installed. The ones I removed, had a .0938 in bore, by a quick and very dirty caliper measurement, so they were 15/16s bore.

I really did not care what bore size they were, but I did need them to physically fit the backing plates.