I am decoding the numbers on a Turbo-Hydramatic 350 transmission installed in a 1972 Cutlass Supreme, and would like input if I am decoding them correctly.

Stamped on the right side servo cover is: 72 LA216 N
I decode this to mean:
72 = 1972 Model Year
LA = TH350 transmission for a Cutlass 350cid V8
216 = Built on the 216 day of the year (August 3rd)

Is this accurate? If so, when was the model-year changeover from 1971-1972? Would this be August 3, 1971 (early in the 1972 model year) or August 3, 1972 (very late in the 1972 model year)? This particular car was assembled in Framingham, Massachusetts. I know that today, GM changes model years over in July. However, I have no idea when model year changeover occurred in the early 1970s.

Thanks in advance for your input!