If your head is the original, it will be an 848 head. 1956 was the first year of production. It raised the compression from 7.5-to-1 to 8-to-1. It increased gross horsepower to 140. The cast number on the head is on the distributor side of the engine, near the top of head, close to the valve cover. In addition, the 848 head casting also features a larger hole for electric temperature senders. Since you have an electric temperature sender, I would bet you you have an you have an 848 head.
