Hey to anyone reading this, I am new here. I am an AG Mechanic and work on CNH (Case IH) equipment and takeuchi compact construction equipment. Been swinging wrenches for 12 years. I focus on engines, transmissions, and after treatment diagnostics and repair. I recently bought the pico basic kit, and currently waiting on it to arrive when they come back in stock! I am here to soak up knowledge, and if possible offer my assistance in anyway possible. I hope each and everyone of you have a great day, and happy EASTER!

Welcome Sean to this community of helpful and excellent technicians. 

I would think in general there is still a considerable chunk of "old" AG machinery out there, let's say 30 to 50 years old. Is this actually true?

It depends where you are in the world. Here in central Illinois everything is newer (10 years old or less). Texas in certain areas is running old equipment however. I work on old tractors, 1066, farmall h like 2 times a year, everything else is new enough for emissions (scr systems only on CNH equipment). I hope that helps answer your question!