I was driving my 2011 gmc on a highway in massachusetts when the transmission decided to fail. my rear wheels locked up and was caused to turn sideways on a highway. my truck was hit by four other vechicles. well the truck got fixed. the transmission was replaced 3 times! with all the same failures. gm needs to check into there transmittions before it could kill someone. 3 times its been replaced and all 3 times my rear wheels have locked up. why? you guys need to fix this issue...