i have a 1970 chevlle ss 454 with a 7 x on the upper right hand corner of the trimtag does anyone know anything about this

Sounds like you may have a Baltimore built Chevelle. The number found in the upper right corner is thought to relate to the gate or cradle the body was assembled on on the Fisher side of the assembly plant and was used for quality control issues. nothing too important as far as we know at this point. My research on 69s built in Baltimore show similar numbers and that is the basic explaination from a former employee. hope that helps Andy