I jusy got a 97 mark VIII LSC about a month ago. The car runs real good but the only problem I have is that around 40-45mph a mean vibration or shake happens and once or twice around 80mph. It feels like when your about to enter a toll on the highway and u roll over the little speed bumps. What is that about???

You need to do a flush and fill with Mercon V fluids. This is the famous "shudder" that the 4R70W trans is famous for.

:I:W to the LvC! :Beer

about how much is it to take it to a place and have the mercon put in??

Depends on where you go. I know at my Dad's dealership its $129.00 I think. Thats using the Rotunda flush and fill machine too.

I just called somewhere and the guy told me $90. I think I may have the same problem because when I get above 50 the car vibrates in the pedals and seat but not the steering wheel (just got new rack and pinion). Do you think the flush would help? BTW I have a 96.