O.K. - That's the part I knew, I'm still wondering what a 1973 GM Body Style 13 is. Is it a Camaro, Biscayne, Chevelle, Caprice, El Camino, Nova...it's something that came with a 350 L65 motor...not that this really keeps me from enjoying my new-found toy...it just makes me wonder and this is the best place I know for answers to this kind of question. If I had the preceding 3 digits in the VIN, I'd be done. The first is a C, the second two are a mystery.
Would a casting number from the intake help? P/N 16436572....oh yeah, kicks, the body style is Fleetside 127" WB and the Protect-a-Plate RPO indicates 3 Speed Auto Hydramatic and the data plate is stamped 5000 GVWR. You're right on about the 6 cyl (S)...and Janesville (J), too. She was a lovely shade of 520 (Lt. Yellow) with Deluxe Heat, Heavy Duty Suspension, Power Steering and Brakes, Full Gauges including Clock (no vacuum or tach

)and an AM Radio. It's all still there and in working order, less the clock. She's a lot further along than the '66, which I'm giving to my uncle to restore.
Ain't research grand...now if only the money were this easy to find.
Thanks for the info and to all for the example of how to do it all the way and right.