I cant get the old hinges off because I cant figure out what bit to use for the bolts(I don't want to strip the head). They are kind of rusty but I did soak them in PB blaster.

Any help will be appreciated

Refresh my memory, are these the large phillips head type hinge bolts?

Yes they are the phillips head type bolt. I cant figure out which size phillips screwdriver or bit is the correct one. I cant get any of them to move. Are they reverse thread maybe?

Years ago when I removed the doors on my 57 Chevy, I went to Sears and purchased an impact screwdriver. It came with various size screwdriver bits and worked very well. You choose the proper tip, engage the screw head and whack the end of the tool with a hammer. This forces the tip to turn counter-clockwise. Works like an impact wrench.

Get the right size screwdiver and try tapping the end of the screwdriver with a hammer while its in the bolt/screw. That will usually loosen it up. Also you want to use the type of screwdriver that has a hex head under the handle(Snap-on) where you can put a wrench on it. Push in on it while your turning and apply pressure to the wrench and it should come loose. If that doesnt work heat it up with a torch.

Impact driver like MalibuJerry said. works every time.
cheers
Steve

Thanks everyone for the help, I'll try it today!

I tried everything and nothing worked. After drilling the heads down far enough to remove them I screwed a nut on the bolt from the back side and welded the center of the nut to the bolt, and used a socket to back them out. This worked very well for me.

I just did the hinges on my 67 and ended up buying a #4 phillips but because it was to long I ended up cutting some off to shorten it up then welded it back on the socket. It worked like a charm.