one site I found said it was a z28 engine ...
Most likely the same folks wrote that site as painted this sign -
It is a RPO-L65 350c.i. small block assembled in Sept of 1972 for a 1973 model Chevelle/ElCamino.
1 = Chevrolet Division of GM
3 = 1973 'Model' year
B = Baltimore, MA Final Assembly plant
419492 = the sequential VIN numbering
T = Tonawanda, NY Engine plant
09 = Sept. month of assembly
18 = 18th day of the month assembly
CKL = Usage Suffix - RPO-L65 350c.i. with TH400 trans, 145HP, Single 2bbl carb.
The CKL Suffix designator was used in two (2) vehicles for the 1973 model year - the Chevelle/ElCamino and the Impala.
The Baltimore plant only assembled A and A-Special bodied GM vehicles - so it could only be a Chevelle in this case, not an Impala (which were assembled in Arlington, TX and Oshawa, ONT. Canada) ...