90 with LT77 jumping in reverse

I have a 200 tdi 90 with a LT77 box and a disco transfer box,
When reversing it feels like a prop is falling off by the way it jumps. Its fine forward tho there is a vibration around 50 in top or 40 in 4th. I have fitted a new rear prop and new uj's in the front one.
There is a bit of play in the front axle, diff I guess, but it doesnt seem that bad.
Any Ideas please?
Phil

Try leaving the hand brake off next time you park. If this cures it, it's the shoes lifting due to incorrect adjustment

harlequin said:

Try leaving the hand brake off next time you park. If this cures it, it's the shoes lifting due to incorrect adjustment

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Got to be worth a try, maybe worth backing the shoes off a bit. will report back

Have backed off the brake shoes but it has made no difference sadly. Back to the drawing board.