So...
When I first got the car @ 82k mi, it liked to do this strange thing whenever you floored it between 25 and 35 mph. It would act like it dropped into neutral. I purchased a 3 year warranty on the car, just because I got an excellent deal with hookups. Warranty guys sent it to local transmission shop, they said transmission was just fine and dandy. Took it to stealership, they determined it to be internal fault. New transmission time.

Warranty company (Guardian Warranty Corp) explained to me that the transmission replacement would not be brand new, but they would warranty it for atleast a year, which made no sense to me. Well, its two and a half weeks later, and I have the car back with a 'new' used transmission.

First to second gear is rough enough to throw your head back at any throttle position, second to third is smooth, third to fourth is smooth, but whenever it locks (I'm guessing I'm feeling the torque converter locking in and out?), it hits hard. So if you take your foot off the gas at 45 mph, and put back on, after about 2-3 seconds you feel the heavy clunk. So basically it feels like the transmission isn't taking the time to shift between first and second, it just does it, resulting in the large jerky motion. Also at 45 mph, when you manually down shift to third and second, it feels like you're gonna snap a tranny mount lol. Any ideas if this can be 'tuned'? Or should I just take it to the trans shop and raise hell? Somethings gotta give.

Can you clarify the year and model (and put that in your signature?)?

You say it'* a 97, but you posted it under the GXP/Northstar section.

I wonder if the "new" tranny has the proper gearing vis-a-vis what'* programmed into your PCM?

What was your old tranny'* gear ratio?

Climb under your car and snap a photo of the tag on the "new" tranny...it'* code will tell us what year it came from, gear ratio, whether it'* got the right type of torque converter, etc. That tag should be on the rear of the tranny, just above and to the left of the differential housing.

sorry, I guess I did screw up. I'm waiting to get to my PC at home to make a photoshop sig but its a 1997 Pontiac Bonneville SE w/ 86k mi.

Well the transmission guy feels that there'* a clutch in the torque converter thats pretty much shot to hell. And he doesn't like the fact that it locks @ 30 MPH and that its causing most of the problems. Sorry I posted this under the wrong section... still getting used to the forum. Thanks guys.