Right about the precups in the Clearwater heads. In the ones I installed the precups were machined flat with the head surface and did not protrude at all. In fact it almost looked like the precup ports were simply machined into the head and there was no precup at all. Does make me wonder.
Black 95 6.5TD, 929 block, 173k miles, 65k on IP, 48k miles on self-rebuilt engine done in '09, 6 L&S Full-torque inserts in outer main crank holes, Clearwater heads, Fluidamper, rebuilt NV4500, 3" downpipe, 4" exhaust, no cat, dual T-stats, 9 blade fan, spin-on 180 degree clutch, Heath hi-flow water pump and turbomaster, PMD relocated, OPS relay mod, Heath PROM upgrade, and Kennedy headlight harness upgrade soon. Now use semi-syn Lucas 2-cycle oil every fill-up which greatly reduces the frequency of DTC 35-36 codes the PCM/ECM throws.