First it would be good to determine what you have. If it is an HG-68, or an OC-3 with 68&amp;quot; gauge from center to center the track will measure 68&amp;quot;. If you can post some pictures it would be easier to tell you what it is. HG&#039;s depending on the year used a Hercules model IXA-3 or IXK-3 engine with the IXK-3 being the most used. About 1949 a change was made to an IXB-3 engine and this same engine was used on the OC-3.