Differences between early 3020s and late 3020s

I am in the market for a 3020 gas tractor and when I get online and look at all the different ones for sale, I see a variety of different HPs listed anywhere from 55 to 77. Was there a big difference between the early 3020 models and the later ones? What improvements were made from the early years to the later years?

Back when 3020's were sold new JD advertised their tractors at pto HP. IIRC JD advertised early 3020 diesel was 64 PTO HP & 70 PTO HP. PS trans were about 5 HP less. You can view the early & late gasoline engine Nebraska test by going to Tractor data then go to 3020 & click on "power test details"(see below)

Well, could write pages on this but there are to primary groups, 1964-68 and 1969-72. The big difference between the two is the hydraulic levers are beside the seat on the later bunch, called a "console". There were other changes as well at the time. There were also many, many other changes along the way.

With what you are concerned with, HP, the earliest tractors (64-65) had an oil bath air cleaner. In 66 this was replaced with a dry type, and many of the NG models were retested at NEbraska, yielding more HP with the dry type.

Most were also retested in 1969 when further changes were made. I know in '69 significant changes were made to the gas engine of the 4020... it went from 340 ci to 362, I think with a longer stroke. I'm guessing the same happened with the 3020 gas engine, as it was essentially a 4 cylinder version of the 4020 engine. No changes in displacement were made to the diesel however.

There is a lot, lot more to this, but this is just a tiny start. Green Magazine printed a 3 series article on 4020 changes this summer, most all of that applied to the 3020 as well. It is very comprehesive, but missed a few details too. It would be the best reference that I know of.

Call Green Magazine. A few months ago, Dan Brotzman wrote two great articles on the tremendous number of changes over the 12 year tenure of the New Generation tractors. While he talked about the 4020, many of the changes would apply to the 3020 as well. The most visible difference is the 1969-72 tractors have the hydraulic controls removed from the dash and placed in a console beside the seat. Also, the diesel models of these tractors changed from the complex 24 volt system to a 12 volt system with alternator for the last four years.

55 drawbar powershift 65 pto powershift 70 hp pto synchro