change the fluid and filter at regular intervals, and turn the overdrive off when towing and you'll be okay. Also, if it shifts down constantly when going up hills and all, just turn the overdrive off.
If you do all that...she'll last you a good while.
Now, I don't tow anything with this truck (doesn't have a hitch), nor is there hills in FL...lol But, this tranny takes a beating nearly everyday just from my type of driving, and, she'll still shift crisply every gear (knocks wood). And, if you let it, it'll occasionally chirp 2nd
(it does have a shift kit, but still)...haha.
But, this is the original tranny at 149,000 miles.