Supposedly, the 1953 Powerglide engine has the
head bolt pattern of the later high pressure engines . It used the valve cover of the earlier low-pressure 235 engines, and the short side cover (as used on 50-53 235s and 54-62 235s/261s).
Check your head bolt pattern against the pictures at the link above. If it is the pattern of the high-pressure engines, the dippers on the rods are hard to explain.
