Technical GM 454 Strange Casting Id.

What did I buy. I've never seen this casting number, and I use those words very loosely. No stamping on front pad, nothing above timing chain cover and only GM-DO with a wagon wheel in front. Anyone seen this before? Thinking some kind of crate engine. Thanks for any help.

 

I think that reads 6M-D
More info needed. Rear main seal 1 or 2 piece? Pic of end of crank?

 

The wagon wheel is a foundry logo. I've seen it on lots of 1950s Oldsmobile castings.

 

Maybe a casting date code? Not a part number.

 

@badshifter is right, post a lot more photos of details.

 

The engine is still in the car. Just clicked in my head that this is a Canada built car, so might be some funny stampings. I'll try the passenger side of the block, asap.