problem you have got trewy is getting the old race out, would be better with the diff out of the axle and the the diff assembley removed from the casting
welcum to the loony assylum, first off if doin green lanes only a set of tyres and sum recovery points wud be needed but iff you intend payin to go onto an off road corse then lifts/snorkel/guards/breathers wud then be on yer shoppin list