GJC
Contributor
All I know is that the yoke knob and the 2nd Stage cover say "Conshelf 20" on them. You may be correct, but the one I have is all shiny chrome. I like shiny things.
Per the VDH archive on the Conshelf progression, the 20 should be satin. The original shop that sold the reg may have assembled a mix of parts or things may have been swapped or replaced at some time over the last 40 years.
The port plugs look like they were from a Conshelf XIV. If it has 3 lp ports and the HP port is 3/8 in, the first stage is a XIV with a 20 yoke screw on it. (I really like XIVs, one was my first reg purchase)
If it has 4 lp ports and the HP is 7/16 in, it's a 21 (my favorite Conshelf first stage).
If one of the lp ports is 1/2 in, it's a 22 or an SE2 (my least favorite because of that 1/2 in port).
Service kits and everything inside those first stages are exactly the same.