i'm not positive but i think with a block # of d2ae it would be a 72 engine which probably would have the open chambers as it is toward the end of cleveland production dates. 73-74 they went to the tall deck modified version for emissions
1970 2-Bolt D0AE-A,D0AE-C,D0AE-E,D0AE-G,D0AE-J,D0AE-L D0AZ-D
1971 2-Bolt D0AE-A,D0AE-C,D0AE-E,D0AE-G,D0AE-J,D0AE-L D0AZ-D
1971 2-Bolt (CJ)
D2AE-CA D1ZZ-A
1971 4-Bolt (HO) D0AE-B,D0AE-D,D0AE-F,D0AE-H

?-?
1971 4-Bolt (CJ)
D2AE-CA D3ZZ-A
1971 4-Bolt (BOSS) D1ZE-A,D1ZE-B D1ZZ-D
1972 2-Bolt D2AE-DA DOAZ-D
1972 2-Bolt (CJ)
D2AE-CA D1ZZ-A
1972 4-Bolt (HO) D2AE-EA D1ZZ-D
1972 4-Bolt (CJ)
D2AE-CA D3ZZ-A
1973 2-Bolt D2AE-DA DOAZ-D
1973 2-Bolt (CJ)
D2AE-CA D1ZZ-A
1974 4-Bolt (CJ)
D2AE-CA D3ZZ-A
1974 2-Bolt D2AE-DA DOAZ-D
1974 2-Bolt (CJ)
D2AE-CA D1ZZ-A
1974 4-Bolt (CJ)
D2AE-CA D3ZZ-A
HO = High Output
CJ = Cobra Jet
BOSS = Boss 351"