HAA - 1950 216 installed with reguler (3-speed) transmission
H = = 1950 model year
A = passenger car
A = regular engine from Flint, MI engine plant = 216

133972 = 133972-1000 = 132972th engine out of that plant in that year
http://www.1954advance-design.com/chev-specs/1950-c-ser.pdf

Find and post the various casting codes shown on this page.

As posted above, the short side cover on a 1950 USA 216 engine is odd. On 1950 USA 216s there was a "tall" side cover (a short cover head was used on Canadian 1950 216s )

One possibility is that the Engine Serial Number is not original (the casting codes will tell us more).

Tim
1954Advance-Design.com
1954 3106 Carryall Suburban
1954 3104 5-window pickup w/Hydra-Matic
The 216 and early 235 engines are not "splash oilers" -- this is a splash oiler.