Getting part numbers is probably the only way your going to be able to tell. But the up side is you'll be able to find a few to bid on and probably find a cheep one by knowing what your getting.
"How do I know what Bosch VE Pump I have or am looking at buying?
The Bosch part number on the Bosch VEs pumps are fairly standard i.e. 0-460-4XX-XXX VE , what are important to note are the 6th and 7th digits of the Bosch Number. The 6th digit indicates the plunger size, 9 for 9mm, 0-10mm, 1-11mm, 2 for12mm. The 7th digit the is the application, 4 for 4cyl., 6 for 6cyl., etc. The specific manufacturers part number may also be on the pump and completly different, for example, the Cummins 4BT injection pump numbers do not indicate plunger size, everyone I have seen to date has been 12mm. Since the 4BT is a 4 Cylinder engine we can assume that part.
3917530 1986-90 VE Series Rotary, CPL 858, 105 HP
3908191 1986-90 VE Series Rotary, CPL 767, 105 HP
3917535 1986-90 VE Series Rotary, CPL 857, 120 HP
3906631 1986-90 VE Series Rotary, CPL 593, 105 HP
3919716 1991-93 VE Series Rotary, CPL 1260, 105 HP
3926831 1991-93 VE Series Rotary, CPL 986 & 1848, 120 HP
The only way to know for sure is with the Bosch part Number."
courtesy of vwdiesel.net