I have a B6100HST-D that we bought off an estate auction. The tractor was loosing water and I put a new radiator in it and it seemed to be running well. Apparently it was still loosing coolant and overheated. After getting it in the shop and taking the head off I had water in all 3 cylinders. I really like the little guy and would like to bring him back to life, but I'm confused about what engine it has in it. Just trying to figure out if the motor has been changed at some point and that it isn't original. According to the tag it should have a 675CC engine, but the block looks like 575CC?