Tanx Baron,
I had a '78 lwb back in 1990 that was a diesel conversion and had an Olds 283 in it. I remember those blue valve covers you are talking about. My current truck had a 5.7 diesel. The TH350 is original as far as I know, but maybe it has been swapped out because it had a fresh rebuild on it. (So I was told. Do fresh rebuilds leave shavings on the bottom of the pan?

) ANyways, here's a pic. This was after my engine BBQ so it may not be too clear.:p See the black ribbed valve covers? ANyone know what those came on?