Frank, I have a 1951 88RC and have found the # you are refering to. The # on the block would indicate it is from a later standard tread tractor (53 or 54, can&#039;t remember which). This engine may have been switched in the last half century, I don&#039;t know. My question for the &amp;quot;people who were there&amp;quot;, Did they match engine numbers to the tractor serial number? Maybe B A Star has an answer.