I just looked over the Big Six info and I bettin' on the 413! The aluminum tag that told about the High Compression head and high altitude engine was on the left front side of the engine just below the head. Are the other numbers there or actually on the front of the block? Man I hope it's still there! You're going to make a Mopar convert out of me! \:D

"I wonder if God created man because he was disappointed in the monkey?" Mark Twain