The .97 heads in cars sold in the US have casting number 603 010 17 20 where -17- replaces -14-. In later years MBUSA sold casting numbers -20- and -22- and maybe others to replace -17-. I believe from gsxr's analysis that there was a progression of improvements to the oil gallery between the timing chain cavity and #1 cylinder. After the metallurgy improvements from -14- to -17-, that is.

The -17- head came in US 90-91 350SD/L, 92-93 300SD and 94-95 S350.

Sixto
87 300D