I'm in the process of replacing a dead RM211 in my sis-in-law's '79 Trillium
Just got the replacement fridge last night, a used Dometic RM2193 that's very clean and works nicely on all 3 modes.
The only other option was a Norcold 323 (same size as the RM2193). Both these fridges are deeper than the original, so some work is involved in fitting them in. Pushed fully in, the fridge will stick out in front of the cabinet by about 3 inches, this could cause problems in some case (front cabinet door in the way).
Sis-in-law's 1300 is a front dinette model, and the new fridge sticking out 3 inches makes it in line with the front of the bench, so that's just fine.
The RM2193 has the burner on the right and the gas connexion at the same position as the old RM211, so no modification required to the gas line. The Norcold has the burner on the left, and requires a longer gas line to reach the connexion. But the Norcold is apparently less prone to flame outs while driving has the burner is more hidden from the wind (my old popup had a 323 and stayed lit most of the time. The RM2193 is known for not staying lit while driving). Otherwise they are pretty much equivalent.