Hung and Jeff are correct. Split cowl was a Service Kit or an Accessory Kit, easily retrofitted to any 152. Serial number will tell you about it if you have the complete serial and a table of serials vs year models.
The information below is from the FAA Type Certificate Data Sheet 3A19
15279406 through 15282031 (1978 Model)
15282032 through 15283591 (1979 Model)
15283592 through 15284541 (1980 Model)
15284542 through 15285161 (1981 Model)
15285162 through 18285594 (1982 Model)
15285595 through 15285833 (1983 Model)
15285834 through 15285939 (1984 Model)
15285940 through 15286033 (1985 Model)
A1500433, A1520735 through A1520808 (1978 Model)
681, A1520809 through A1520878 (1979 Model)
A1520879 through A1520943 (1980 Model)
A1520944 through A1520983 (1981 Model)
A1520984 through A1521014 (1982 Model)
A1521015 through A1521025 (1983 Model)
A1521026 through A1521027 (1984 Model)
A1521028 through A1521049 (1985 Model)
Charles
