Torque to yield, head bolts...

I remember those cars well. Most problems didn't involve the engine itself......although they certainly did have their problems. The most I saw were transmission problems, because when the engines ran right, they had too much torque for the transmission and usually broke them. Diesel Grand Prixs used to be a dime a dozen because most were sittin in somebody's yard with a bad transmission.
When those ran they ran well. I drove a demo Century on a couple vacation trips. 35 mpg but they only had TH125 trannys I believe. Not a beefy transmission for a diesel. When GM came out with the 6.2 and then the 6.5, the 700 R4's just came out. Of course they put them behind a turbo 6.5 in a 4 wheel drive. The salesmen would sell them to a farmer that would use it like a grain truck, pulling big wagons of shelled corn in overdrive. Glad I don't work there any more.