Transmission Problem?
 

I have been noticing a "flat" spot in fifth gear between 2600-3000rpm. Is this a known spot on the fuel mapping that just has a rumbling/hesitation problem? When in in that range and on the gas it makes a rumble that I can feel throughout the car. When I get off the gas and coast in the range it feels smooth.

Also, for future reference, is there anywhere to get rebuilt 944 transmissions? I know 944online rebuilds them, anywhere else?

THANKS!