Question - Casting Block Number

I recently acquired a 1967 Dodge Dart GT convertible with a 273 V8 with 2bbl carb. I tried to find all the numbers on the engine, but due to the exhaust system on the passenger side and power steering unit could not find those numbers. However I was able to find the casting number on the driver side below the exhaust manifold. Had to use a small mirror but made out 2806030-273-3(or 9). I believe the first 7 numbers indicate it was cast in the 1966-1969 time frame, and the next 3 numbers indicate it is a 273 cu. in.. But I cannot find out what the last number stands for and cannot plainly make out if it is a 3 or a 9, maybe even an 8. Does anyone know what the last number indicates?