In reply to above posts, the only car with series III in 04 is the Grand Prix(probably because 04 was a new model year of the GP). This guy has a Buick Lesabre, which never got the series III.
zzyzzx, The aluminum coolant elbows proabably didn't come on any 3800's, and your 99' Alero would have plastic ones for sure. You can see the new aluminum replacement in my second photo above the arrow. I used a light coating of Permatex Ultra Grey RTV silicone on them because I heard of people's aluminum elbows leaking.
CBR, if you think he'll listen, ask the mechanic to use the Aluminum lower gaskets, aluminum elbows, and maybe even the whole upper manifold for the Dorman one with the smaller diameter EGR. Not sure most mechanics will take direction from a customer like that so it's up to you lol. Maybe even bring in the part numbers.