I have no reverse after gearbox rebuild. Only things changed was bearings and seals. It does shift into reverse but it's a little hard to shift but nothing happens, the wheels wont spin. All the other gears work and shifts great. When I had the gearbox on the table it was hard to shift to reverse sometimes but when removing the selector detent on the reverse selector side it shifted to reverse great but with the detent in, it was hard to shift to reverse

 

 

Does the detent move fairly freely by hand? It should obviously offer some resistance, but between finger and thumb you should be able to collapse it.
If you can - then thats not part of the problem.

Assume you can get fifth fine? If so, then its unlikely to be poorly setup linkage.

Afraid beyond this it will be box out. I'm sure you've now learnt this now, but always bench test a rebuilt box

 

I going to remove and check the detent. Fifth gear is a little hard to shift to with the shifter when engine is turned off but when driving it does shift to fifth okay but reverse is hard to shift. I have had the gear lever assembly open and changed the plastic bushings

 

Do you need to push the shifter down to put it in reverse?

 

I removed the geae linkage and tried to shift to reverse straight on the gearbox and it still didnt work so I guess something is wrong inside the gearbox