I had to replace a cracked frame mount (the one that connect the strut rod/cross member/ trans mount) on my MII. The problem is the the longer of the two bolts is fused to the old insulator.
A silence here usually means that not many people have tried it before.
If you want new parts you are likely to have to take a sample to the local nut and bolt supplier. The local home supplier (Low's, Home Despot) may carry something similar, but you want Grade 8 or better, which they likely dont have.
Another option is to get used bolts from a dry area of the country where corosion is less likely.