I have a 96 'burb with 143k, 2 wheel drive 5.7 Vortec and 4L60e that I just picked up a couple of months ago. While driving at highway speeds in OD I get a slight hesitation from time to time, either like the transmission slipping or the motor giving out. It is never more than a second or so at a time, sometimes in succesion, sometimes once every couple of minutes. I can't tell if it is the tranny or the motor. I am inclined to lean towards the tranny as the motor runs great at idle, or standing still in drive with the foot on the brake giving it gas, with the exception of what sounds like a manifold leak (but thats another thread!!). Clue #2 that it is tranny related is the fluid on the tranny dipstick is aerated. It does not smell burnt, and it is not to nasty looking either, and the level is correct on the stick.

Any ideas?

As always check for codes transmission and engine.

If fluid is aerated plull transmission pand and check filter and filter pickup.
Make sure it has the right filter in it.
The deaper pans take a taller filter.
MT

Went to drop the pan and change the filter, but there is a cross member there! Do I support the tranny with a jack and remove the cross member, or is there a tool to get up and underneath the cross member? Because of the lip on the pan I cannot get in there with an open ended wrench, and there is no way my 3/8 socket is getting in there!

Any ideas?

Some you have to slide the crossmember back some but first.
Try taking mount bolt lose jacking up the transmission.
A woble socket helps to get the pan bolts out.
Good luck
MT