Thanks Panel for the info. I noticed the same M on my differential housing as well. Very cool to get the history on that.
The head is an 848, haven't had the valve cover or starter off to find the rest. The block casting code is elusive. I am pulling the motor tomorrow... if it is a 261 code I will take it home. If not, it goes back in the truck for the next guy. I will update once I get that far. Thanks all.
James
