Good chance I got it wrong but I believe it could be the 15th week of 2008.

The "MC" inside a shield indicates Motor Castings foundry.

Darned if I can remember the location of the stamped in machining code (not a direct date), but MP never required Cummins Recon to document it or provide the decoder ring for it anyway. The Cummins markings were for the most part useless during my time working with these gems.

After the megablock went away casting date wasn't tracked on the block any longer, only the machining date was tracked by a stamping in the front.