2005 suburban problems

[dubmans92]

Hey guys. My stepdad has a 05 suburban 1500 lt. We recently changed the diff out. In order to do that we had to remove the sway bar. We got the new diff in and works like a dream. Now the problem is that the abs light and the traction control lights are on, and it says serve stability system on the info center. Can somebody whats going on cause my stepdad complains about the "mofo lights are on agian" everytime i see him. Ps he thinks we damaged the abs sensors on the rear end by sliding the axle back in.

 

 

2nd question same truck. We've tried to get it inspected but with many fails mostly on the evap system. It passed with my stepdad filling the tank full, but the side effect is it smells like gas even when the gas cap is closed. Then the other problem is that the engine light comes on when the gas is at a certian level in the tank.