1999 SL2 slight transmission leak

Hi guys, 99 with 87k miles, just developed a slow leak. Trany shop says $500. to take apart and reseal. They say it's a 2 piece unit that is split open to repair. Question: is there an external seal fix available? Is it a major job to reseal? $500 sounds like 8 hrs of master work.
Runs, drives & shifts beautiful, just alittle puddle at night.
Regards,
hakebros

$500 seems probably about right if its actually one of the transmission case gaskets.