2004 SR5 V6 with 140,000 miles.
I bought it with about 120,000. When I bought it I immediately switched to Amsoil 5W-30 motor oil. I also changed the diffs to Amsoil Severe Gear. Recently, I had the dealer service the transmission (flush), and change the coolant. I also asked about changing the steering fluid, but they said changing ps fluid wasn't necessary.
For the record, before I changed these fluids, my truck was still running factory fluids. And I have the four speed (non WS). I'm also running stock battery.
I'm going to replace the serpentine belt soon.
This truck is a beast. No hiccups.