Hmmm.  Okay, I do follow.  From what you are saying my truck should
have bolt on lines.  However, I gave the GM dealer my VIN number and
the part I received has clip on ends.  After I got home I compared the
lines.  They are slightly different from my old ones, and I brought
them back thinking they were incorrect.  He double checked again and
the same parts came up.

When I look under the truck, I see big bolts where these lines attach.
The only way to remove these bolts was to remove the oil filter adapter
as well, and because it didn't look like it was leaking, I didn't want
to do that extra work for nothing (this is another mystery, the adapter
seems to have square holes on the two bolts ends holding it in, the
kind you would put a ratchet adapter into to remove them, but they are
smaller than 3/8" and bigger than 1/4").

I'm starting to wonder if I'm going to have to take off the adapter and
try to crank on those nuts and see what happens.  If it works I can
bring the part back to the dealer and clear up this confusion.

Assuming it is a bolt on, does the nut screw back up towards the body
of the truck, or do I unscrew it down towards the oil line and remove
it with the line?

Thanks for your help, by the way.  I can't understand why there aren't
any books mentioning this very straightforward area.