RH Rear window regulator
 

O.K., I know to use the search function, and I have, but I do not see anything that helps with the problem I have. I have the door panel off and the new regulator ready complete with motor from Rock Auto but I cannot loosen the bolt that attaches the regulator to the window. The head seems to be 7.5mm as an 8mm box end is too big and a 7mm box end is too small. Do I need to order a 7.5mm wrench or am I missing something? Also, what in the heck is the fastener on the backside of the regulator. Seems to be some sort of 4 pronged fastener. None of the Diy's adress this problem I am having. A little help anyone?