Chris
Thanks. I put a Quaife into the box in the car in situ, so am comfortable with that.

So if the box has mechanical shift webs it is a C503 and could be 164 12v (mine in car) or 164 24v (which I think I am rebuilding)
For this box that I am now trying to assemble out of other bits, I want to make sure that when I get to the end (if I do!) that I have all the right elements in place as a spare. Right clutch setup push/pull, diff that wont break etc.