Leo - There isn't one stamped anywhere on these oil pans. The way to confirm what it is must done through the shape of the pan side mounting flanges, the mounting bolt count, the drain location and the baffle location/orientation in the bottom of the pan.

Many different threads on pan identification already exist that discuss the difference, but I couldn't find a single thread that covers all the identification points in one place. I think I seem to recall that the side flanges with the bump out on the passenger side is a feature for the 1955-62 pans (1954 and earlier 235's and 261's had straight rails and a different mounting bolt pattern/count), while the horizontal baffle was related to 1955-57 235 and 261 pans. The later 1958-62 pans had a vertical baffle due to a different style oil pickup if memory serves me correctly.

Other will probably chime in with added info. Or maybe someone remembers a better thread that discusses the subject???

~ Dan
1951 Chevy 3 window 3100
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