2004 Ford Taurus SES
Trying to change the ABS module out.
Need to remove the battery tray - there are 4 bolts.
However, one of them is smaller and has has a weird round top:
(not sure why, the Ford Parts website shows they are all the same but the other 3 seemed to be 10mm standard bolts and came right out).
Have the standard Sears 100 piece socket.
Tried every metric and standard socket and none of them fit properly.
It's almost like the 6 sides are not standard socket sides?
Tried a vice-grip, won't budge either.
Any idea how to remove this bolt and what is it ?