DO NOT WELD ON YOUR HITCH!
12mm x 1.75mm x 40mm hardened bolts is what they are. I went with the 10.9, I think, hardened metric bolt. Go buy the 12mm x 1.75 tap and tap out the holes. It is just major rust in the hole, very easy to do properly and install yourself. Once the holes are tapped just lay the hitch in your lap as you lay on your back, lift it up into place and use your knee's for the other side to hold up. Swing around and throw in the other bolts, simple really. Note, if you can't get the bolts at the dealer just find a good quality hardware store, check the auto parts houses or like what I had to do was go to a industrial fastener supplier I use to get them ASAP.
Good luck.
