"K"
Cigar Grand Poohbah
Bwahahahahahahahahahhahahahhahahhaahaahahahahahahahahhahahahahahahahahhahahahah!
Yea, that 3.8 was in almost every GM car from 1962 until the 200x's. One of the best V6's ever developed. You'd be a punk to replace it with another 3.8 though; go V8 bro!
Actually, upon thinking of this more, it sounds as if you may have thrown a rod. Best to get it checked out by a professional.
Try another local mechanic. Dealerships are a retarded ripoff.