I have purchased a used set of Lufkin I.D. micrometers 1-1/2 to 32 inches. It is missing the handle and a few wrenches are corroded that I would like to replace.
The inside mikes you have are interchangeable with those made by Starrett tools, at least the handle and wrenches are, and would make good replacements.
This part of the Lufkin tool line has not been produced since the late 60's.
Pratt and Whitney produced some of the Lufkin line for a while, but it was eventually phased out except for the tape measures. Cooper Tools currently produces those. I collect Lufkin tools, and make most of my purchases on eBay. That would be your best bet.