I have a 1972 7520 and a 1975 8630. The 7520 has an intercooled 531 turbo 6 cylinder diesel engine and is rated 175 hp. It does not have a "live" PTO.I wish it did for the grain cart. I like mine quite a bit but it isn't near the horse the 8630 is and it uses more fuel to do the job. The axles are 3 3_8 diameter compared to 3 5_8 diameter on the 8630. The 7520 has a good cab for what it is but isn't as quiet as the 8630. The hydraulics are good and we are going to use it this spring on a team of drills if its not needed to help with tillage. In my area a 7520 will bring the same money if not less than a 4020. If you want a good cheap horse, this is the animal. One more thing, the 7520 has the same motor as the 6030 two wheel drive tractor.