Dave,
I'll call Sheri Moon at TAD for you. I don't recall if they are open on Saturday or not, but they could be.
It appears that the model number of the elbow is stamped into the base. See if you can make it out. If not, she can probably tell you what it is anyway, from the engine serial number. It's likely that it's a Bowman cooler, rather than Perkins.
When you send the email, give me a good time to Skype you, assuming your bandwidth is still good enough for an audio call.
Talk soon.
Jack