Jeremy,
I thought it looked like cu pipe fittings, trouble is cu pipe fittings have their own size. 1 1/2" cu pipe is 1 5/8" OD. Iron/Steel pipe is a completely different animal, exhaust pipe/tube might work. I'm not sure on exhaust tube sizes but I think they have a 1 5/8". A good shop could make up anything you need, they can expand or re-size to what you need.
I would bet that the elbow is brazed onto the down pipe, is the down pipe cu also? May have created a mess by cutting it off,,,,,hope not.
Good luck.