They are the same regulator and use the same rebuild kits. The only differences are the number and placement of the LP ports on the 1st stage. Even the Xii changed the number of ports between introduction in 1972 vs. the end of the run in 1977. Kits can be got from the Vintage Double Hose web site;
from another thread:
The VI had 1 HP, 1LP. Its second stage had the 7/8" exhaust valve.
The XI had 1HP, 2LP. Its second stage has the 'magnum' exhaust valve, with a calypso style exhaust tee. It is easily identifiable because it still used a metal yoke screw.
The XII had 1HP, 2LP (early) and 1HP, 3LP (late model). Its second stage had a magnum exhaust valve with the common press on tee, and a Teflon second stage lever. Early models are easy to pick out because they use a yoke nut, while later ones used the C-Clip. They all had plastic yoke knobs.
The XIV has 1HP and 3LP (though always a 3/8" HP port) and the same second stage. It looks identical to a late model XII except for the stickers.
The conshelf 20 (not vintage, but just for your edification), has the same conshelf XIV first stage, but a plastic second stage. The second stage is internally identical to the metal one in the XIV.
Incidentally, you can get a SE or 22 first stage, in which some models have 4 LP ports if you like diving a drysuit. It looks identical to the XIV first stage, except with 1 more LP port. I have two 22 first stages hooked to XIV second stages, and that is what I currently use for my tech rig.
