I didn't think the damper location made any difference to articulation :?
Anyway, the later (say EFi) models had the dampers both ahead of the axle, that's what a Disco is you know, a poor man's RR.
The later axles had the same hubs, disks and pads, halfshafts etc but the bolts for the trailing links are bigger so you need to check this, I'd swap for the later arms anyway which you can change by fitting new chassis bushes. The diffs are also stronger and have metric bearings in them.