Depending on year could have the 6spd, 8spd or 10spd.
The general doesn't really have a service interval on much anymore.
You'll never fully drain a torque converter unless you cut it in half.
A simple drop pan, replace filter and aproximate 8ish+ qts it takes will be just fine.
If towing, I don't see an issue with 25k. 50k would be fine too.
If just normal driving, I'd take it to 50k.
6spd takes Dexron VI
8spd takes Mobil 1 HP LV
10 Speed takes Dexron ULV
No dipstick either. Need to fill through pan or plug Depending on trans and check at temp, which varies by trans too.