If that tranny was never serviced in 186k, it's toast. No doubt about it. Go to a scrap yard, buy a tranny ( they normally give 30 day warranty). Sell that thing within 30 days. There are a gazillion of those tranny's sittin on a shelf in scrap yards. Ask the scrap yard guy who can do the install for you..... ( they know everybody). Installation will be cheap in da hood. Wash it, wax it, clean up the interior. FOR SALE signs all over u-it. Don't mention a word to potential buyer about tranny, Put it on Craigslist or whatever social media oulet you can find too.