Rover V8 gearbox's

Good News I used the 3.9 engine and it is immense! thanks to those who advised me ... now i have gearbox problems... i run a LT77 gearbox, and its gone like it doesnt want to go in gear... its got plenty of oil in there so im thinking maybe its a major problem. Can anyone advise me on how i should tackle this problem? should i get another gearbox, or are they easy to work on? If i were to get another are there different gearbox's that are better and less troublesome...? HELP?

could it be a clutch problem ? the 5 speed one out of the old sd1 is v strong as is the old 4 speed bedford cf (bell housing needed), these are the only 2 i have used so cant coment on any others.. if ya go for the bedford, look for the factory built icecream vans, they have a lower 3rd gear..

The rover boxes in general are s**t your better going for the transit mt75 box easier to get hold of and are good for 500 bhp you just need make a conversion plate can sort one out if you strugglin