I've heard several bolters saying different things. Since I decided to do a complete engine rebuild, I also rebuilt the three speed tranny at the same time. I didn't want any "weak issues" down the driveline so I decided to pull the bushing. VAP sells a special extractor to pull the bushing but it is on perpetual backorder. If you are lucky and have the dowels holding the front bushing in place, I would suggest pulling the front bushing before you drive the Okie in if only to make sure that the tube space between the front bushing and rear bushing/seal is clean. Mine was not. Regarding the splines, we need to ensure that they are not jagged in any place to avoid tearing the rubber seal as you drive the Okie into the tube. Not too sure how much a visual inspection will reveal, but I plan on using my bare hand on the splines as much as I can to hopefully feel any rough spots which would need dressed with a file or sandpaper.
