There are 2 bearings on the pinion shaft. Front, near the yoke , and rear near the ring gear. I have seen where someone loosened or changed the yoke and didn't get the preload back on the pinion bearings correctly. What case is it?
If you use the bearing splitter, make sure you set it up in your press as seen in the pic, with the bolts in line with the steel plates, so you dont bend the bolts in the splitter
You can use C clamps to compress that front drum if you don't have an arbor press. I rebuilt the 727 for my GTS restoration. There's some info in the build thread at the bottom of my response.