It was a little hard to read this thread because I had to keep moving my screen back and forth to read it due to the big pictures, so if this was already discussed, forgive me for not seeing it. Anyway, as I recall the 4 x 4's and maybe vans had that aluminum pan, but the cars and boats had a metal one. The aluminum one is deeper as I recall.

Years ago I rebuilt a 4 x 4 4.3 engine for a boat I had and it came with the alumimum pan. It was too deep to clear the bottom of the boat, so I had to buy a new metal pan from Volvo Marine. There are also several generations of that 4.3. Basically, there are early engines that have no balance shaft inside, and later ones that do. Parts from the early ones sometimes do not fit the later blocks (like intake manifolds) and I think oil pans also can be different.

When I did the marine engine I was going nuts because my old boat motor was a 95 and the motor I built for it was a 97.........Chevy made a change in 96, so lots of my old boat parts would not fit........the oil pan being one of them. I finally had to bite the bullet and pay something like $ 250 for the proper 97 marine pan, and associated oil pump pickup tube.

I think the suggestion the guys have of hitting the junkyard is a good one, but be careful because the gasket configuration varies from year to year, so you have to have your old gasket with you or your old pan to see if the one you find at the junkyard is the same shape.

Don