I've worked on a handful of them with around 200k. The timing chains get noisy and they tend to eat oil. The bushing on the rear differential is common also, if you drive on a bad bushing it will eventually ruin the driveshaft bushings too. Check
https://www.creative-steel.com/home.php for replacement bushings. I've used them on a few customer cars and they are a lot better than the stock bushings. If I think of more ill update, I like them and would buy one for myself if I could afford a cadillac.