LDV CONVOY REAR AXLE AND SUSSPENSION?

Hello,
I Have a coach built LDV Convoy (V-reg/2000) bus 2.5 turbo Diesel
I have been having problems with the air suspension.stuck down. i have had it in several local garages (and The AA) trying to fix the electrical side of this ,but none of them could fix it!
so i have decided as i have been told the air bag controller (ECU) is now obsolete and not made any more. i cannot find anyone to fix it or test it!
so plan B is to replace the hole air system with salvaged old springs
, shocks and rear axle,
i have been offered a whole axle and shocks springs local to me . but they are from a 1999 LDV convoy
i was wondering weather this would fit or is there a compatibility issue.??????????????
also as my wheels are the smaller type (for the coach built) the stud spacing will be different. can i remove the wheel drums and swap them over or do i need a set of back wheels too??