What you are looking for is the bypass fitting - it is GM part #88891743. Metal is preferable to plastic because the plastic ones will eventually degrade and leak, and when you try to remove it, it will break off inside the lower intake, causing you no end of grief:
http://jlg.net/photos/bonneville/bypass_fitting.jpg

www.gmpartsdirect.com has them for $7 plus shipping. Most dealers should be able to get you the metal replacement. It will be $15 to $25 at the dealer.

You could replace the bypass hose itself while you're at it - it'* only about $3 or so at Autozone. It'* the hose that runs from the water pump to the lower intake.

Both of these parts are the most likely source of a coolant leak on an L27 with over 100k miles on the ticker. Both are fairly easy to replace, but do it on a slightly warm engine. As the lower intake manifold cools, it contracts (shrinks slightly). This can make it harder to get the bypass out.

Can't seem to find a metal elbow for a 96 vin K?
Anyone know if they make one?

I didn't find one either yet... going with plastic.
Popa Tim