You may not like my answer but;
I have a 1990 Fleetwood Southwind gasser. I needed a new radiator for the rig. After much searching for a pre-built radiator I had the old radiator removed and a NEW ONE BUILT.
I dealt with a local radiator rebuild shop called LILAND radiator. They have been in Syracuse for about 35 years. The radiator was made from all new parts. The bad news is $2500.00 for the new radiator. That is just for the radiator not anything else.
The exact name of the place is Liland Trade and Radiator service
3154320745