H 197. Code for August 19, 1957. Date the block was cast. 3837004 is also for a 1957 235 block. Clean the flat area behind the distibutor mount to find when and where the engine was actually built and its application. Check the top of the head on the manifold side. Should read 3836848. With the valve cover off you can see a similar code to the H 197 cast in the head.
