You have a Oliver model number 7 spreader. I have attached a scan from the literature for this model. The lettering for both the horse drawn and tractor models was the same. The literature is dated 1942. We can tell you that the first one built in 1950 was serial number 22334, thus assuming that they started with serial number 1000 which is common you can see how many were built prior to 1950. Your was probably built some time shortly after WW II.