All that does is increase the pinion bearing pre-load..... which is almost certainly not his problem. And in truth is probably just smashing the crush sleeve until the pinion bearing pre-load is so damned high that it honestly feels tight to you again. Not because the BL is corrected, but because the bearings are so bound up that you don't
feel any loose play anymore.
On a side note: That is an exceptional plan for really extending pinion bearing life.
To the OP, first of all, the truck/differential is probably
fine, and will drive perfectly for
years just as it sits. If you hooked it to a 15,000lb trailer every day for 10 years it would likely be fine...
However....
If things
must be Peeeerfect for you, then yank the cover as was already mentioned...
As was mentioned using a magnetic base attach to the flat portion of the housing face where the cover goes. Then placing the dial indicator so that it strokes TANGENT to the ring gear (otherwise the value read is USELESS) do as stated above and while holding the pinion PERFECTLY still gently push the ring gear to the pinion, zero the dial indicator and then gently rotate the ring gear until it stops in the opposite direction. Note the value. Then do it a few times to make sure you have a consistent value. Now you're looking for something in the 5-8 ish range. That's 0.005 to 0.008 inches. Since it will undoubtedly be higher than this, you will have to pull the caps (making sure to KEEP them oriented such that they go back on the same way, same side) and yank the carrier taking care not to lose or mix up the shims if they are outside the bearings as they usually are. Take shims from the end opposite the ring gear and add them to the side closest the ring gear to decrease BL. Also note the preload. If the carrier just falls out in your lap you've got a bearing problem most likely. If it's just loose, then add some shims to snug it back up. Do this on the RG side (usually driver's side) and skip swapping shims from right to left as the additional shims will not only increase the pre-load but will also decrease the BL when added behind the RG.
Now if that seems a bit ridiculous, then just drive the truck like everybody else does and stop worrying about it.