I replaced the thermostat now trucks normal operating temp is above normal mark.

What is your question?

The truck heats up quite fast then usually stays around the 3/4 mark as if it was a normal operating temp. This didnt happen until i replaced the thermostat. Also my 4 wheel drive makes a really loud grinding sound and once its in 4 wheel its stuck

What makes this problem better or worse?

Sitting at lights tends to make the temp climb but it doesnt overheat

How long has your 2007 GMC Canyon had this problem?

About 6 months