big block engine lift brackets

[big gear head]

I've been looking at old threads of engine lift brackets trying to figure out what I have and I've got some questions.

I have a set of brackets from a '69 427 and a set that I got in a big lot of parts that I can't identify. The 427 rear bracket has a L stamp and the front bracket has no stamp that I can find.

The other rear bracket has a M inside a C and the front bracket has 3994055 and a small V stamped on it. This one has longer legs than the one from the 427, and it has sharp corners instead of rounded corners.

Is there any information on the applications of these brackets? I've seen where the '70 front bracket had the small hole for the fuel filter, but not sure what that is all about. I'm just wondering how many different versions there are of these brackets and what they were used on.
Thanks.