Have you priced a new or reman Mopar/Cummins vacuum pump? The least expensive price we found was $1400.
As an alternative, we have a limited supply of NOS (new old stock) Wabco pumps (quantity 40) that we've purchased. To bring them up-to-date we changed the seals to a dual lip design and added new o-rings and we also include the pump to gear cover gasket. Instructions included.
'91.5-'95 Vacuum Pump Retrofit
You can use our Wabco '96-'02 vacuum pump on your older '91.5-'95 Turbo Diesel with the 3-piece design pump. However, you'll need to make some modifications to the system, namely a longer oil line (#3934396).