350 SBC Motor Mount Bolts - Which are correct?

[greywurm]

I lost a bolt for my driver side motor mount yesterday, the center bolt of stand to mount, and the passenger side is loose (might have loosened on the 5 minute return trip home).

I have done some researching and it looks like I might have been using the incorrect bolts, but I am not sure how I would get a nut on the bolt between the mount and the engine block.... it was hard enough lining up the engine to the stand to get the center bolts lined up!

Anyways, I attached the pic of the bolt I used from the 250 I6 I pulled and these ARP bolts from summit.

Would the lack of a nut on the opposite side contribute to the bolts loosening and coming out?