I'm not familiar with the #'s after the G-85 you reference. If you tell your parts vendor you need a air warmed G-85 w/fins, he should be able to supply you what you need.

I don't believe you can purchase just the finned housing- you'll have to buy the whole unit.

As far as yours freezing up, it's a symptom of not having warm coolant running through it while it's dropping the lpg pressure. As propane drops in pressure, it begins to "boil"- although when it boils it becomes extremely cold.

At below -40 degrees, propane is liquid. At-39 it begins to "boil"- to keep propane in a liquid state at room temperature we keep it pressurized. As the regulator begins to depressurize the propane it begins to boil. To keep this boiling at bay, external warmth is needed. The only air warmed vaporizer/regulator I know of is the Century G-85.

The key to your success with this process is mounting the regulator in a warm air stream.