Outer Limits 4x4 Board

This make take a while to explain so bear with me. I own a 95 Jeep Sport Wagon 4.0l petrol with 4speed auto. done about 190000km. have full service history upto 185000 and had a mechanic just do a transmission service replacing fluid. The gearbox has always made this slight whirring noise as soon as the transmission is locked into reverse or forward gears (when not moving) and is noticeably louder as moving forward. There is no slippage in the gears but seems change quite quickly into 3rd and 4th after a spurt in 1st and 2nd(don't if this is normal for these gear boxes) Kicks back fine when I need it to but will kick into 3rd and 4th quite quickly at the end of a spurt of power. Smooth gear changes (no clunks or flare) just this whirring sound thats got me a bit worried. After the transmission fluid was changed at 190000 (last service 146000) my mechanic reckons hes checked the bands etc, no problems. He believes it could be a pump or solenoid. Any advice would be appreciated for a newby like me, just so I know that a mechanic isn't going to feed me alot BS and want $$$$$$$.This car is a pleasure to drive and kicks arse with power.

ask him what fluid he used - I have heard of people having problems unless the Mopar trans fluid was used.

Just a thought.....

Thanks PK....I actually read an article on the net how Chrysler had made a announcement to change the type of transmission fluid to use for that model wagon. Will have to try and find it and post it up. I ended up taking it to a transmission mechanic today because it was driving me nuts. He reckons it either the pump or torque converter, either way they had to drop the gearbox.?????? Does that sound right????. Would one the symptoms being that it drops into 3rd and 4th prematurely ?????