This is again off topic. I have a SC, it was a great car while it ran. Most power and the best gas mileage of the 3 T-Birds I had. My issue with it was it gulped antifreeze and ruin the bearings, twice (I bought that way to begin with but, didn't know why the bearing were out). I understand that even the 4.2 version of the V6 does the same thing. What's with that?
I was impressed with the forged crank but, why did they put in that odd main bearing journal?
I wasn't on that design team, but I did work on (struggle with) head gaskets in the early 90's. We got the mandate that all asbestos had to be eliminated from head gaskets. It turns out that asbestos was covering a lot of sins in the old engine designs... The replacement materials such as graphite just didn't cut it on the older engines. Multi-layer steel needed much finer surface finishes and more consistent clamp load than what you could get on the old stuff, so that was out. (Many new engines are using multi layer steel now...)
The 3.8L was an iron block / aluminum head combo so it was super hard on head gaskets. After deep thermal shock tests on the dyno, you could see the head gasket getting abraded away from the differential expansion. I bet you were leaking coolant into an oil return...
The 3.8L block was originally supposed to be aluminum. That was before my time (early 80's), but they found that the aluminum blocks would literally fall in half during dyno testing. Management just punted and tweaked the block tooling for cast iron. I wonder if the offset bearing shells are a by-product of those tooling tweaks. Not sure on that one...
Sorry this got so far off the rails, but it does speak to the idea that factory parts (like rods) can be far from perfect! I wouldn't hang my hat on OEM quality control vs aftermarket either. I was a foreman at an engine plant, so I've seen things