I don't think of yesterdays tractors as necessarily being 30 years old at all. For example, the Caterpillar Challenger "tracked" agricultural tractor has been around that long, and tracked tractors have been around much longer than that. However, for example, you go past a Deere or Case IHC dealer, and you will see tracked tractors built as after thoughts, on the chassis of articulated MFWDs. That's very clear on the Deeres for instance, where the cutouts for clearence for the large front tires that used to be there, are no longer there in favor of tracks, although not Christies suspension. The same of the Case IHC tractors that were Steigers that are now painted red, and the front and rear sets of tires have been replaced by independent sets of tracks. Those two examples that I just gave have been around for 10, maybe 15 years. Yet, you can still get them with tires, although compaired to the tracked counter parts, are yesterdays tractors (technologies). The foot print of a tracked ag tractor is clearly superior to that of rubber tires, yet these tractors that I mentioned that are gaining in popularity haven't been around for 30 years, and the tractors that they are replacing, far from 30 years old, are yesterdays tractors. And...2 wheel drive tractors are still readily available, but smaller 200 HP range MFWDs are everywhere, making a few year old 2 wheel drive a tractor of yesterday.
Yes, there is a website known as yesterdays tractors, this one, and a darn good website it is. I will always be forever grateful for the knowledge handed to me by many that I now consider friends. However, yesterdays tractors reach far beyond this website, by decades, even a century or so, before computers existed to have such a website.
As a parallel, when I was a high schooler, my generation thought that we were the baddest that ever walked planet earth. An elderly teacher, nearing retirement had enough of us and informed us that her grandparents informed her that they were informed by their grandparents that they too thought that they were the baddest that ever walked planet earth, doing many of the same things that we did, decades, centuries before we were born. The only difference? With time comes improvements and availabilities of technologies. Technologies have a way of making things that are seemingly new today, yesterdays...., over night.
In my opinion, yesterdays tractors can be as new as a hand full of years old, thanks to technologies. My opinion.
Mark