Fiat is not doing great as far as the car company goes. Iveco is a strong division as is CNH. CNH is profitable and from what I can tell is not really under the financial thumb of Fiat as much as Iveco is. Kobelco and New Holland construction equipment are very large globally and turning a profit as well. At one time I owned the largest fleet of Iveco trucks in Indiana, we beat the heck out of those things and I can't say they were the best medium duty trucks, but they were worth what we paid for them and we got our money's worth out of them. I think they build them a bit light for their duty rating, we destroyed some of the suspensions but I don't think it was the fault of the trucks so much as the demands we put on them. It is a shame they pulled out of the US.
Worst case scenario with any profitable division of a multinational corporation is that the divisions get sold off to generate cash for the parent company. So under if Fiat bleeds too badly, it could sell off CNH and CNH could end up with a new owner. The tractors would likely still be the same. By the way, Fiat received a $2Billion payment from G.M. and right now is in decent, but not great shape. The Fiat family still has the controlling interest in Fiat motors, they seem to have big egos and really want their namesake car company to thrive. That may be a long term problem if they decide to bleed their profitable divisions, but so far that doesn't seem to be an issue now.
Hope that explains a bit about them. But there is no real concern about the stability of CNH. They are, by the way, the largest producer of AG equipment in the world. I have no idea where they rank in tractor sales, but they do produce a lot of non-tractor equipment in additon to tractors.