The physical dimensions of the Quaife and Jack knight are the same so If your JK were to fail its a straight swap for the Quaife unit. lubrication and service are really identical except the JK has the one piece gaiter that you have to fiddle the spacers through and whatever side fails the whole thing needs to be changed so its a more challenging job.
However a lot is written about loosing the centering but this isn't the case for either rack. Yes mark the rack position in relation to the crosshead brackets for a rough alignment but if your steering is fine prior to the removal then as long as you maintain the steering wheel position and don't adjust the the track rods all is usually fine. to keep the rack/pinion position I remove the rack end rubber caps and I have two large washers that slide over the linear rack gear each end and sit against the outer body. I then wrap a strip of rag arount the rack outside the washer and zip tie it in place
