I have recently removed the carpet from my Imperial, and I am now in the process of scraping the remnants off the floor pan so that I can address the rust. What is that stuff? It looks like undercoating. Was this normal? Was there paint under it--I can't tell, about all I can see under it is rust or what could be either bare metal or primer/paint. Surprisingly, even with as much rust as there is, yet again no rust through. Also, the bolts that hold the body to the frame (at least I presume that is what they are for) seem to be quite rusty. Are these special bolts, and if so is there anywhere that I can get them? I figure as long as I have things to this state I may as well replace them (plus I would hate to have them break when I really need them). Is there anything else that I should replace while I am replacing the bolts? Thanks, Mark Elliott 1964 Crown 4 dr