Late 1955 235 engines still used shims.

I'll check the 56 through 58 manuals (if no one posts the year that shims were no longer used).

added later:
It looks like 1956 and newer 6-cylinder engines only required shims if a bearing cap was replaced. Maybe someone with more experience will chime in on this one. I did not need to use shims on my 1960 261 engine.