Thanks to all for your ideas!
I suspect that the rockers are the incorrect parts, since their casting numbers do not match the numbers in the master parts catalog. I hadn't considered the possibility the assembly was done wrong, I'll check that too. The squeaking noise is what caused me to look at the source. I too suspect an oiling problem, but with the engine running the oil flow at the one valve stem squeaking appears to be the same as the others. My catalog lists six exhaust rockers with the same casting number (839001). It lists 2 sets of three inlet rockers with casting numbers of 838997 and 838998.
I have a 1940 version of the engine too and it has the three sets of casting numbers listed in the catalog. They show some wear. I am looking into just getting these re-ground and re-bushed; if needed. The shafts may need replacement too, but I won't know that until I get in there more.
I am uncertain I have a serious enough problem with the way these ride off center on the valve stems. Any thoughts? I am trying to keep the truck as stock as possible.
Thanks.
P.S. I think the stems are "off their rockers"!
