427 motor mount holes
 

I am posting this only because it's so time consuming to research in the real world much less the club forum. Here's what I ran into.

While putting my 427 side oiler, C5AE-A using #2240 (l) and #2241 (r) motor mounts, I found when installing the left side motor mount the holes didn't seem to line up.

The header was in place and it was pretty hard to see how it didn't line up. Long story short, after Fing with it for a couple hours with the header in the way, making minor "adjustments" along the way to help it fit, turning a perfectly good motor mount into swiss cheese I decided to start again fresh the next day with new motor mount.

This time, with the header removed, It was clear the hole in the mount closeset to the 6 o' clock position was 3/8" lower than it should have been if it were to line up to the 427's motor mount bolt hole. The right side installed exactly as it should have. The two other holes, the top hole as well as the hole closest to 4 o' clock were both fine. The holes in the new mounts were the same as the holes in the mounts I removed from the 428 I was taking out.

One 3/8" hole later I was able to install the mount as intended albeit with a slightly longer hole in the motormount. This seemed like a better solution than only using the two which lined up.

Hope this helps someone else one day.