Like I said above, the stock nuts didn't appear to have a serrated flange. I bought self locking nylon nuts with matching washers (the same setup maximum motorsports includes with their solid mounts) and yes m14x2mm nuts. Made sure they were grade 10 and zinc plated.

Those summit mounts look like the vert mounts. So if you have stock mounts from before 1990, they may lower the engine a bit. I ordered my prothanes from https://alteredfox.com/collections/e...prothane-61905

I think what ZR means is that the OEM style mounts (probably rubber) have more flex than polyurethane (energy suspension, prothane and summit) so they don't transfer as much vibration to your car. You can get OEM from rock auto but I think you have to reuse parts of the metal bracket.