Adjust your vac level, and change fluid with synthetic ATF, sub one quart of Trans-X for one quart of that ATF
Change it again in 1k, then keep it changed every 20k

see what happens

Never known the trans to whirr, that's a rear end differential noise

If the transmission slips in every gear and no amount of adjustment helps then it's time to think about a rebuild

do a search on B2 piston also

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)