My design goals were light weight, ease of installation, it had to fit without modifiying the tail wheel bay opening and it had to steer via the rudder servo with no pull-pull cables.
The E Flite 10-15 nose retract is too big and weighs too much to put in the tail of this plane, so I modified one of the new tail wheel e-tracts that FMS uses in their 57" P51. The total weight of my retract assembly is 37 grams, including the wheel and mounting plate.
This tail retract unit comes stock in the FMS Version 6 and Airfield Version 3 57" Span P51D Mustangs. I had chosen it because I think it is the smallest and lightest servoless retract that is commercially available and it's already steerable. I highly modified the unit to fit into the existing opening and to steer via a pushrod linkage. I will update the blog and outline the process in the next week or so.