In 79, all busses came from the factory with a catalytic converter.
Jump ahead to 1993.  The PO of my bus gets the bus emissions tested
and it passes WITHOUT a catalytic convert.  I buy the bus in May of 94
with same exhaust as when emissions tested.  This test is good until 
Feb. of 95.  When Jan. of 95 rolls around, the exhaust gave out.  I
replaced it with the one piece J.C. Whitney model(w/o converter)
and have had success with it.  The good part is that even though the
emissions were scheduled to be tested in Feb. of 95, they NEVER sent
me a letter.  Since I'm 9 months overdue, Im getting kinda nervous.
So I call and get a few quotes for exhausts systems with convert.
and they tell me in the $1000 range.  Yikes!
So, the emissions people "forgot" about me for now, but what to do 
when they find out about me?  The only real problem I'm having is
finding the long j-tube which connects to the heater boxes and
then to the cat. convert.
Any ideas?
Paul