Chad is a childhood friend who has a 1959 Oliver 550. This isn't it but if memory serves this ought to be close. I think his might have the exhaust routed underneath the axle. Tractordata.com has this listed as being produced from 1958 to 1975. 17 years for a single model to be produced is a pretty good track (or field) record. Chad said he mostly uses his 550 for snow plowing and mowing and will put it in a show with proper arm twisting.