I have been trying to dig through some of the older LS engine swap posts to find this answer but so far no luck. I purchased new clamshell engine side mounts for a 4th Gen Camaro to use on my LS swap into an 83 Z28. My plan was to buy the basic cheap motor mount (Rock Auto) to get the clamshell and then upgrade to the poly inserts before installation. The issue I have ran into is that the clamshell has a tab on the bottom that seems to be in the wrong place. The tab lines up with the rib and the mount will not sit flush with the engine block. I came across a post where I think the poster indicated that this could just be cut off, but it was vague due to the original post talking about a different tab. So I am trying to confirm that I can just cut this tab off - pic attached for clarification. Not sure if the part was just manufactured incorrectly or if I should get a different part #. Everything else looks correct, bolt hole pattern is correct and it looks like the poly inserts will fit once I drill out the rivets.

 

The tabs are/were locator tabs. You don't need them. I believe the aluminum blocks are a little different and the tab is there so you can't install it in the wrong direction. The iron truck blocks used different mounts and fit differently with the web in the block there

 

Awesome - thanks scooter !