pinion bearing vertical play

[roky]

i'm guessing at the answer to this, and its "0", but want to check with you all -- after examining my rumbling differential, with the cover off, i find no metal shavings, pretty good looking ring gear and pinion, with little backlash, but side gears that are scored -- but on to the intermittent rumble -- when i grab the flange attached to the pinion, up front where it connects to the driveshaft, i can push up quite a bit, probably 1/16" -- i'm thinking the pinion bearing is no good? -- anyone ever replace these? -- and if i can't replace the bearings, what years/models benz would have a center rear end section that swaps in, so i can start looking -- my axles seem fine

thanks, roky