Looking at the differences between a few Chevy 216 and 235 Oil Pans over the years.
Chevy 235 Series
1955-56 GM Chevy 235 Engine 2nd Series C# 3836233
GM Block Casting 3836233, 1955 Changes
GM 235 Engine Motor Mount Locations
Photos of various GM Chevy 235 Engine Blocks showing where motor mounts to the frame.
1950-51 GM Chevy 235 Engine Cast# 3692703
50-51 Chevy 235 Engine Block details for casting 3692703.