mine had done this too

was at TOTD and front wheels werent spinning

it viscous coupling and cts do them for around £250 and about £50 fitting just have to take your box to them
even as VC has gone and rwd ,mine seems to be 4wd at times on the road
its not just a case of it being rwd now ,if you want it rwd you will have to convert it using 2wd parts .

hope this helps

my escort cossie done this and im thinking of going 2wd conversion