I have a PRM500 gearbox attached to my JP3 in a narrowboat. No problems except that I have not found the sweet spot where the gearbox will go into gear without crunching. I have dropped the revs as low as I dare but even at its best, there is still some crunch, especially for reverse. I have no tachometer so don’t really know how slow I can get it but I do find there is a spot where it just brings the revs back up a little so slowing it down further risks a stall which is not desirable as I am generally using forward/reverse when approaching immovable objects!
I am interested to hear your opinions. Hopefully I have just missed something obvious or perhaps crunching goes with the territory!
Cheers
Steve