Cab 13 C-15A Forklift Engine ID

[RichCam]

Hello,
I've attached some pictures of a Cab13 C-15A forklift with 24" tires. Unfortunately, the owner of this rig has passed away and his estate sold. This rig is probably bound for the scrap yard in the spring. I have the opportunity to salvage what I can from it. I'm trying to identify the casting numbers on the engine block but I can't see them. There is an engine mount blocking my vision and my digital camera isn't picking up the GM XXXXXX casting #. The area where the serial number should be is smooth. It looks exactly like the pictures from pages 1,2 & 3 of the C15A-04 Chevrolet Spare Parts List booklet except that it has been modified for 12V verses 6V. It has the 1.8391 oil filter, hand activated starting motor, carburetor, distributor, 4 blade fan, etc. The only thing that appears to be different is that there are frost plugs visible on the RS of the block. Does anyone have any idea when Chev would have started to install frost plugs in the 216?