That's pretty high for 60 MPH IIRC. Sounds like either a TC issue or perhaps the solenoids in the replacement transmission, especially the one for the TC clutch, could be your issue. I have also heard of a bad brake switch causing a no OD scenario.

 

My old transmission did the same thing. I'm having bad luck with the car. The problems never seem to end and I've only had it for a year

 

Resources from by Monte Bookmarks:

Peoples Transmission: P1811 - Maximum Adapt and Long Shift Mode Chevy, Pontiac, Saturn, and Buick Front Wheel Drive Vehicles

No 4th Gear

How Much Do You Know About The GM 4T65E Transmission?

 

I thought of the 4th clutch hub too, but it seems awfully coincidental that both trans. would have the same problem.
As for the P1811, Sarah said there are no codes. This would also rule out the TCC solenoid since it should throw code P0743, or code P0740 or P0741 for the TCC circuit.
A bad brake switch would throw codes P0504, P0703, or P0719.