Want to get a new power brake booster, 1973 Duster.

My 1973 Duster has power disc brakes with 10 inch rear drums. I've got all the parts to replace the brake system, but the vacuum booster has been tough. Advance and Autozone can't get it, Summit and Year One don't seem to have it, or at least, based on the description of what they do have, I'm not sure one will be an exact replacement for mine.

I don't care about factory appearance or correct colors, I just felt that I should replace the 51 year old booster while I'm doing the rest of the brake system.

Anyone know where to find what I need?

Here's a photo of what is in it now. This photo is before I took the excess add on junk out and the insulation off the AC lines.

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