I have a 2004 g35x, ABS, AWD, traction, and slip lights, periodically come on and transmission shifts really hard. I'm thinking maybe wheel speed sensor or ABS sensor but not sure, my code reader doesn't show any faults.
Any thoughts?

 

Sounds like you are on the right track, but even more likely a camshaft sensor. Go see an auto parts store and get your code read.

 

Verify your tire size does not exceed 3% difference in overall diameter front to rear if you have staggered tires. Check your brake fluid level. TCM codes can only be read by the dealership since they are not part of OBD2. NDS might do TCM though???

Have you been keeping up on the transmission fluid change intervals?