Hi Alan the only info I have at the moment is this :-

Tamiya recoil wiring

WHITE WIRE = Start recoil (+) fire
BLUE WIRE = Battery negative (-)
GREEN WIRE = Battery positive (+)

Now for the fun bit. I have seen a HL recoil rewired to work the " right " way which is fast recoil and slow return. I'm sure YHR made the same mod to a HL unit here a while back. The only issue here is the mod I saw was wired to work with an RX18 and you have to use a microswitch on the recoil unit to control the firing cycle just like a Tamiya unit ( pm me if you want the name of the other site where I read about this mod ). So the thing is you need to see how Tamiya wire up there recoil copy it and in theory it should work fine. It's a bit of work I know but if it works yon can then use Tamiya DMD's and MFU's between your tanks. Pictures show how I have modified my Tamiya recoil wiring to be plug and play by cutting and splicing the origional wiring with a Futaba servo extension lead so I can plug any recoil unit ( provided I wire it up right ) into my Tamiya electronics. I have done this with a HL Stug and it's a bit of a tight fit but it all works bar the recoil which I have to modify to work the "right " way and wire up the same as my Tamiya Tiger 1. I have pluged the Tiger 1 turret into the Stug's electronics and ripped off a few shots and everything worked OK.