$18 coolant seal... yeah 18...with that said, all the auto part stores have that middle seal - and claim its for the 3.6, it's not, it's for the 2.8... so the only option was GM

installed back there

that's the end of the motor replacement
Need to align it then start figuring out its issues.... like the windows not going down.... it needs wheels/tires. One of the wheels is different then the rest and not one tire is the same manufacturer.
That said, a/c works and it should clean up nicely.... then drive the wheels off it.