Inliners International Forums General Discussion Engines 261 origin

I'm curious what this engine came out of. The casting number IDs it as a 261. It has a March '59 date code. Stamped number is S0403XXM. The Xs are stamped in, not hiding numbers. My 'little book' lists S code as a '55 235 from a 4000 series truck.

I'm suspecting this may have been a replacement engine put in a '55 and stamped with the original engine number to match the title. But the XXM part throws me. I don't recall seeing any engine numbered like that.

Comments?

Cletis,
I'm a retired firefighter and we had '54 Chevrolet Brush Rigs with a 261 in them and a five speed manual transmission. They were good rigs too especially for our off-road work. Those were 6 volt units. Then in late '55 they bought two more with the later '55 second series cab. Still 261's but now 12 volt systems. All gave great service.
Normbc9