I am trying to get the front rotors off a 90 f-150 4x4. Where I am stuck is getting the front off the manual hub. The allen bolts are pretty rusted and I am not sure if I can get them to turn. My question is what size allen key do I need? It seems to be in between every set of allen keys I have. And any ideas on how to break these things loose once I do find the right size allen key? Thanks.

 

They are sometimes torx too. Look close. If it is an allen it is metric.