K5 Body Mounts

[Critter]

I got all of the bolts and old body mounts removed. Unfortunately the PO had welded all of the bolts to the floorboard. Thanks to a lot of help from JTRUX and his grinder, we got everything removed. Anyway, to make a long story short, I don’t believe any or my bolts are original. I would really like for someone to help me out with the diameter and lengths of these bolts. The ones that were there are too big to go back into the new washers that came with my Energy Suspension kit. Also, the diagrams that I have seen show that all of the original bolts should be carriage bolts, except the one right under your feet in the floorboard. Is grade 8 entirely necessary? Has anybody had trouble with using a grade 5 under normal conditions? I have a feeling my floorboards would crack before I broke a bolt. I appreciate any more info.