Thanks Victor, but I believe that's the diameter. I'm wondering about the length.
Your 1957 posts should already be 1". When threaded in the guitar, they have about 1/2" above the top, and 1/2" below.
If you choose to replace your originals, get these from Philadelphia Luthier Tools rather than from Gibson. These are nickel plated brass like the originals in your guitar. The ones Gibson sells and puts in all their reissue guitars are steel, and there is a discernible difference in the sound with the steel posts vs brass. Steel is more brittle and favors higher frequencies. Brass is more consistent across tonal frequencies and has a far more pleasing sound (to my ears). https://www.philadelphialuthiertools.com/bridge-and-tailpieces/abr-1-bridge-thumbwheel-posts-brass/
Great reply and info. That’s an alternative I have considered also to get deeper mounting of the abr posts. What do you believe is the reason a second thumbwheel increases sustain? I see in your photo that your two thumbwheels are stacked together and also appear to either be touching the top or are close to it. On my LP the thumbwheels are not close to the body like that and wouldn’t be even with two stacked. In that case would you still stack them together at whatever height is needed for the proper/desired action setup? If this does in fact increase sustain it’s a quick, easy, and inexpensive alteration that doesn’t harm the guitar and is easily reversed. I’m guessing maybe the second thumbwheel helps to stabilize the first so there is less “slop” of the thumbwheel on the post and maybe in turn provides better contact between the bridge/thumbwheel/post connection?
