Depends on the quality of the reman transmission, most use the cheapest parts so you are stuck with garbage internals that'll maybe last till its out of warranty, or maybe not. A transmission shop that you can trust is the way to go, they'll give you the best route to take as to go with a rebuild or a reman unit. I'd get it rebuilt because you can specify upgraded components to keep the transmission operating properly for many many years. Brownish fluid typically means its contaminated, old, and has been hot. Whichever route you take on the transmission, install an auxiliary transmission cooler. These transmissions die because they get too hot, and from lack of regular fluid changes.
I had a transmission rebuilt in my 93 Ranger. It lasted about 13,000 miles and blew up again. I had a no-name shop do the rebuild, they just used whatever cheap crap rebuild kit they could find and went with it. I think it maybe went 13k and about 2 years on that transmission. After that I just sold the thing for a parts truck. Then my 88 Bronco 2 came along and this time went with a reputable transmission shop, who took the time to do things right and updated and upgraded stuff so it would actually last, plus installed an auxiliary cooler that should have been on it in the first place. In almost 5 years I've had the vehicle offroad, in snow, mud, sand, etc. Never had any issues at all with it....shifts great, shifts are a bit firm, but better than slipping into gears as transmissions tend to be setup in today's cars which causes excessive heat in trade for you can't feel it shifting LOL. I'd rather feel the shifts, and know its in gear, not slipping between gears and burning up bands and clutch packs. With proper service and cooling these transmissions aren't quite as bad as they seem. I honestly don't trust them, I would rather have the old C5 that was in my 84 Ranger or a manual transmission in my Bronco 2 but it is what it is and if it blows up again I may go down the route of a C5 swap. Granted I'd lose overdrive but I could care less I'd rather have a more reliable transmission LOL.