If the regular visc Mobil1 ATF has worked for you, just order some online. Pretty sure various autopart stores still have it listed, along with walmart/summit.... Around here, Autozone, Napa, Oreilly still have plenty enough.
Autozone clearanced it out so I grabbed a few quarts, along with some Royalpurple. Not in stock doesn't mean discontinued.
RoyalPurple recently switch from regular visc to low visc.
Redline D4, Torco HiVis, and Amsoil ATF are some good alternative choices.
And, don't forget Pennzoil:
Pennzoil Platinum High Mileage Automatic Transmission Fluid is a full synthetic ATF designed typically for older generation transmissions.
www.pennzoil.com