Hey Francis,
Congratulations! Those ain't no old military buckets by the looks of them. Those look brand new-or close to it! (facelifts?) And it looks like you are on your way to the holy trinity of off-road vehicles. Unimog, Tatra...(in my case it's a Hagglunds BV206 6 cylinder)... (but I know that will start a few arguments)
. Before I try and answer your question my question to you would be: Can the Tatra be profitable in NA? I just finished 6 seasons of snow removal with a Unimog 1700 (1977) and it never let me down. Not once. So we have the same question in the Unimog community-with the cost of the trucks plus expensive parts and lack of service network-can a business make a profit using these machines? My Tatra is mostly a collector piece with the odd stint on a movie or TV show. I think if it was thrashed every day it would require quite a bit more attention.
Now, with regards to parts...and I will add the proviso your results may vary-and also the other Tatra owners on here may have different opinions. I have bought parts from 4 or 5 companies now including the Tatra factory. They are all fairly helpful and usually have someone that speaks English (Czech doesn't appear to be an easy language to learn but it's on my list). Skarab has the best website (or at least it did last time I looked). Best prices and quick service so far has been ATH. Don't want to bore everyone here with more of this so I sent you a PM. Cheers.