I have a 1957 Oliver DDH logging tractor with a Carco Model F winch attached, Serial Number "F4.267". Have searched E-bay for a service/parts manual. All the items refer to a series number, for example Model F Series 7, Model F Series 5 etc., and they all reference a specific tractor manufacturer (but no Olivers!). How do I identify which series I have? I was told by someone that the series number probably referenced the specific manufacturer tractor that the winch mounts to, so from that one could suppose that the series number refers to the external mounting hardware (but this is only a guess). Since my serial number starts with "F4" an assumption could be made that it means Series 4 but I'm only guessing on that. I have not seen any Series 4 for Olivers listed on the web, although there are some for other brands such as AC and IH.