I'm at a loss and looking for some help. Actual part names are not something I'm good at and for the life of me I can't seem to find these anywhere. I'll attach a few images to help with my explanation. 75 FJ ambulance door bolts screw into a threaded piece that is usually inside the four holes in the images. I am missing those threaded pieces and don't know what they are called or if they can be found somewhere. Thanks for any help!