A 1976 truck 440 will be stamped "6T440T" The first digit is the year number, they stopped using letters before then. The first "T" is for the Trenton engine plant where the engine was built. The 440 is self-explanatory. The SECOND "T" means it came in a truck.

Sometimes the stampers were careless, after all the engine ID code was primarily to allow a Mopar mechanic to know what he could expect in the block before opening it up. (So if it had 0.001 or 0.010" under bearings or oversize pistons stock from the factory it wouldn't come as a complete surprise.) If the stamp set didn't get hit squarely or if they put something in a slightly different place didn't mean squat.
ChryslerCorp didn't build cars to be restored. They built cars for their dealers to sell and for customers to drive.

R.

PS: Mopar, NEVER SAY NEVER!