Contact Landis Zimmerman at Zimmerman OLiver-Cletrac. The phone number is 717 738 2573, address is 1450 Diamond Station Rd. Ephrata, Pa. 17522. Labdis and his brothers are experts on Oliver crawlers and I am sure he will have the information that you need. I owned a 1963 OC 4 but sold it two years ago. I now collect wheeled Olivers. The OC 4 was a neat little crawler.