Replacing pinion yoke

Is it hard to replace the pinion yoke on an 8 3/4? Is it as simple as removing the nut and pulling it off, and putting the new one back on? Or is there some special process to do it?

pretty much yes if it's a 742/741. You have to anchor the yoke to R&R the nut & takes the right puller to draw the yoke off. A 489 with the crush sleeve needs the pinion to be dissassembled and the crush sleeve replaced or a solid sleeve added which is a better setup anyhow.