Hydraulic control for a D2 5U

I have a 1949 S/N 2887 D25U with a 2A blade and #44 (?) hydraulic control. The problem is that it is an early unit (S/N 4W😎 with a 3 position control valve. I would like to add a "float" position as on the later (S/N 4W485 and up). My local Cat dealer got a good laugh when I inquired about a 7F5200 changeover group. Anyone have any suggestions where to find one?

Jack

One of the engineers that I worked with for years had the same problem on his Case dozer so he put in a 1/4 inch, 12 volt, 2500 psi rated valve between the two work ports for his float.

Honestly I have never tried it, but he says it works fine. It's just a thought if you can't find the parts and need something quick.