Matching up O-Rings

I had to replace the radiator in my 1997 Chevy K1500 5.7 4x4. I got the radiator yesterday and put it in, but when I went to put the oil cooler lines back on, the O-rings were gone. I called NAPA and AutoZone and they said if I bring one in they can match it up. Problem is, I don't have one, they are both gone. Is there a way to look up some schematic that would provide that kind of detail to let me know which O-Ring it needs? I'd hate to dig all the way back to the other end to unhook it just to dig out the ring at the other end to match it up...

Nevermind. I figured it out. I went to GMpartsdirect to find out the part number called the dealership and they have a couple that are an exact fit.

Jeesh, sometimes you forget Chevy built the thing, they might know. You get to the point where you forget the dealerships exist....

Jeesh, sometimes you forget Chevy built the thing, they might know. You get to the point where you forget the dealerships exist....
with the price they charge for OEM parts, hard not to forget 'em.