I do some a/c work but have never messed with this BEHR unit.

But I wonder if the unit found in the 600 would be the same on the inside?

I have found when restoring one of the Thermo-King units I normally have to use parts from several of them to make one working unit. There were at least three of the 'Kugle' units for the 110 and 111 and at least two of the '108' Thermo-Kings. All of the interior parts of each series interchange except for the front plate with the vents and knobs.

Let us know how this works out.