RPM's high in overdrive???
 

After doing some gear ratio and tire size calculations i have determined that while cruising in OD my truck is running at to high rpms. I have the 2500hd with the 4speed auto, 4:10 gears and stock 30.5" tall tires. Given those numbers and the internets infinite wisdom my truck should be between 1800 and 1900 rpms while cruising at 60mph on a flat road. Unfortunately my truck is at approximately 2300 rpms. Im curious if anyone here is experiencing the same thing and if there is a common solution to this problem. Just to put it out there, i am sure im in OD. While driving i down shift into 3rd gear to make sure it in fact switches gears and it does. My 3rd gear rpms are actually right where they are supposed to be at about 2700 rpms at 60mph.

Is the converter locking up? That might explain that small of a difference.