I have had a few, my old IH, model H and model 340, had been about bullet proof since new, the H was a 1948 and the 340 was a 1961
the H ran every time it was needed and sat some times for yrs not used, a zillion parts out there for them too, but they are a little on the small size, I used mine to drag a 8 ft drag disc and never had any issue's doing so, that or a cultipacker , Only really used it for food plots
But original owner bought it new in 1948, and I took over there farm and it was there untill I sold it last Summer(2015) ran like a champ and never needed anything but basic up keep
the 340 was same deal, original farmer had it since new, but it seen a bunch of work from 1961-2014, had a 3 bottom plow, 2 row corn planter, and dragged them 8 ft disc a LOT better, was about 49 hp or so, and it too, never not started or had a sinlge motor or running issue
but ANY old item, the biggest issue will be HOW It was cared for or NOT!
not all owners treat things the same.
but these older tractors ,m were built a LOT heavier than new one's of TWICE the HP, have a look at weights on things, and you will see, and that weight is your friend when it comes to tractors and pulling things IMO and it also makes they last longer. REAL steel and iron on them , made to last, when there was a pride factor in brands and wanting a reputation for building long lasting tractors
NOW< they only want them to last long enough to where a owner won't complain so much and then buy again!! thinking they got there money's worth out of it!
disposable JUNK is made today at HIGH price tags!