I haven't had much luck researching what engine I have. I'll give you the truck info. 1951 Chevy 2 Ton 6100 series 137"wb 98HP with 16,000 GVW Dump. The question is the engine?? Block numbers are as follow 3835499, GM4. Is this a 235 (1951) or a 261 which I thought was a 1954 engine. Any help would be great.