Right firstly my car is a 1997 r cross country 2.5 turbo there's no drive in 1st or 2nd but moves in winter mode reverse seems to want to go back but it locks up now reading up on these they engage 4wd in reverse straight away I think my problem is down to the VC tho don't know how to check it also it can not be push backwards any one know how a VC works
Welcome to the forum! Info on the viscous coupling here: https://www.volvoclub.org.uk/tech/850AWD.pdf It is for the 850 but as yours is an 1997/98 model it should have the old type mechanical system. There is a freewheel unit too. I doubt it would be the VC or freewheel unit as even if they locked up they wouldn't impede the movement of the car. Could be something in the rear diff catching when reversing. One way to check would be to remove the propshaft and get the car on a lift, then start the engine and engage reverse and see if anything in the front drivetrain is stopping it reversing. One other thing it could be is the handbrake shoes have delaminated (friction pads have come off) and are moving around causing the lock up in reverse (but are ok when going forward). This is probably the first thing to check as it is the easiest thing to do. Good luck!
the back wheels turn freely
Hmmm, OK. Another thing to try is disconnect the propshaft temporarily (six bolts on the prop joint by the VC) and raise the rear wheels off the ground. Then turn both rear wheels at the same to simulate reversing, if they won't turn at the same time then your problem is somewhere in the rear diff. Otherwise I would suspect an angle gear or gearbox issue, checked by doing the same thing, disconnect the prop and try and turn both front wheels at the same time.