Caliper ID and rotor markings

[Maynard]

My front pads are screeching, so I took a look at them. Yep, it's time.

Been thinking about upgrading the rotors and calipers, so took a close look at them. I thought the calipers are D52. I wasn't necessarily expecting to find a D52 marking, but neither did I expect the A64 I found. Is that just a casting number or is there such a thing as an A64 caliper? Couldn't find anything on the 'net.

I thought the rotors would be marked with a MIN thickness. I rotated them, used a bright light, a wire brush and a pair of cheaters and never found any markings. Are they on the rear behind the dust covers?

Don't think it matters to the discussion, but it's an '84 K2500 Suburban with 6.2.

Thanks.

[nvrenuf]

The min thickness is marked on the back side.