Vee_Que;c-146064 wroteYou can run a normal speedo drive from the box using a few 240 84-86 gearbox parts.
I wasnt 100% sure but suspected this may be the case, at a minimum you would need to change out the output shaft, extension housing, drive flange, speedo output gear rear bearing, etc.
If you were having the AW71L rebuilt it would be worth doing. It means complete disassembly of the transmission though as the output shaft needs to be changed from the inside.
I do have all of the parts needed to do it that you are welcome to if you ever want to go down that path. It may even be worth having it done to your spare transmission and then swapping them out at some stage?