If it's leaking then yes I'd say it's on the way out. However I'd strongly recommend you buy both rear shocks off the breaker car as those shocks will have worn differently to yours. Ie mileage, road conditions, the speed over those road conditions. I'd also recommend getting the fronts too to have as spares but that's just me.
I've done a bit of research and discovered that the magride communicates with the instrument cluster, CAN gateway, ABS and headlight range. So you will need to get it coded I suspect.