there is the issue. there is no technical drawings for any of those, at least not locked away in a dusty filing cabinet at Getrag's HQ.
You'd basically have to take a worn one and its matching gears and first make a duplicate of it then build the friction surface back up till it does its job properly again. it would be a bunch of messing about to get it just right since short of taking apart a known good unit... of which I do have.
basically getting the proper metals and buying them in bulk is the easy part, being able to recreate it in G code that a CNC mill can use to program is the ultimate challenge.
my neighbor and I were going to do this exact thing actually, but he's since changed jobs and no longer has an entire machine shop at his disposal.