The two rubber mounts are inserted into corresponding holes in the radiator support on the driver's side of the radiator. One near the top; one near the bottom. The two bolts go through the driver's side radiator flange and into the rubber mounts. Tighten them just snug or the rubber mounts will pull back through.
I have one of the last of the NOS radiator supports and had to enlargen a pre-punched hole to get both rubber mounts installed. An aftermarket support might be even worse.
What does the pass side of the radiator use to mount it on the Rad support?