My vac pump quit yesterday. When I called Cummins I found out they are on national back-order. On top of that, they have gone up in price almost 100%. I researched prev. threads and found Delphi makes the vac. chamber, part # POD-4342. I went on their website and found they make the vac pump for 7.3 Fords, and it uses the same vac chamber. I bought a reman vac pump for a 7.3 from NAPA for $116, and swapped chambers with my pump, because this is almost always where the failure happens. This solved my immediate problem,but I wonder if someone sharper than me, might be able to find a source for the vac chamber alone. It would have to be FAR less costly than a complete rebuild.