Transmission should be watched closely... the E4OD has a hard time with high mileage. If you have it serviced or do a fluid and filter, drain the converter as well. The TC's are just as hefty as the transmission itself and a lot of old fluid stays in the converter otherwise. Have a look under the air filter when you replace it. Check for excessive motor oil in the bottom of the box. Its a sign of a dead PCV valve or worse, dying rings and valve seals. If it doesn't see 4WD often make engaging the t-case and the front driveline a monthly habit if only for a few miles.