First off, a Flxible, how cool is that!
There is a casting posterior of the machined surface that reads, "CON4 H31 0
The CON4, pretty much has no meaning except that the engine came off of conveyor belt 4.
H31 0 is the date code and in this case the block was produced August 31, 1960. H is the eighth letter of the alphabet, 31 is the day followed by a number 0-9, which repeated every 10 years. In this case 261’s were only produced from 54 thru 62.
There is another number, on the same side towards the front of the engine that will further identify your engine. Post that and we can tell you what block you have. The head has similar numbers and a date code as well.
