Were all 6.2's n/a from the factory or were some of them with turbo.

As far as I recall a were N/A with exception of aftermarket turbo kits added to them, I think though a 6.2 could be special ordered with a Banks turbo kit

Still need to pull the oil pan to see for sure but when i noticed the turbo exhaust manifold it made me wonder.I'm trying real hard to run this used motor some before i start tearing it apart.Was told it didn't have but 40,000 mi. or so on it.It sure looks rough.

IIRC the 6.2 had a GM dealer option in '90 for a Banks as TD stated. I was looking into putting a turbo on my '85 6.2 Burb, but got discouraged because of the feedback I heard. The 6.2 with a turbo was a screamer, but it came apart most of the time. Probably because when they did the mod they didn't put gages on so they just fried it or blew it up with too much boost. Just an obsevation. Good luck.