A833OD Reverse Gear interchange?

I've been having problems with my A833OD sticking in 4th so it is now out and on the bench. During inspection, the points on the reverse gears appear to be fairly rough so I am thinking about swapping them with parts from another OD trans I have.

Per Passon's book, there are different reverse idler gears and sure enough mine has no markings but the parts idler does. Best I can tell, the 1-2 slider is the same and the reverse gear teeth on the cluster are all suppose to be the same.

The trans out of the car is an '75 iron box and has the 18t 4th gear setup while the parts trans is an aluminum case out of a truck (I think) and has the 20t 4th gear setup. So I know stuff like the cluster and input won't swap, but the reverse idler and slider are unclear to me.

So can I swap the slider and idler from the parts trans? Or am I going to run into problems if I do so?

Reverse has been rough, but it's not unbearable, I would just be all the more careful if I left it alone. So it isn't an absolute that I do this.