My montes original 3100 had the intake gaskets fail around 100k. Had a buddy with a 3100 Grand Am with a head gasket failure around 150k, but his had recently overheated due to an unrelated issue - it seems like the iron / aluminum combo engines are more sensitive to that kind of thing than iron/iron engines.

But to be honest, neither were really a big deal. Being a traditional OHV setup, even a head gasket change is not a massive task, especially since these cars are very open to work on. Even if the failure rate on those gaskets were 100% (which its clearly nowhere near that), I still wouldn't shy away from buying one because of it.

Every engine out there has some kind of issue, these are certainly way on the easy end of the spectrum.