TWilkening, if he's wanting an olds or Caddy with a diesel I wouldn't automatically write the 5. 7 off. Get one with the DX block (80 up I think), the main bolts screw in deeper and they had fewer problems, plus they have roller cams. From what I read if you install a set of ARP studs for the mains and head bolts the 5. 7s will live a long time if you warm them up properly. There is a guy on the Diesel Page with a early 90s Chevy 1/2T that he built an Olds diesel for and swapped in. He's pretty happy with it, says it's faster than the 6. 5 that was in there (whatever that's worth) and he "claims" 30mpg.
Vaughn