I'm wondering if the first generation Cummins 6BT is a source for an 11MM pump head? The 6BT had a Bosch VE up till ~1993 when an inline "P7100" replaced the VE.
If we can find a 6BT VE pump identification number it'll tell what size head it has. I know the 4-cylinder version (4BT) has a > 10MM pump head - when equipped with the VE pump - some of the VW guys are using the 4BT pump on a TDi engine to make a "mTDi".
"Bosch produced VE pump in two shaft sizes...17mm and larger 20mm mainshaft pumps. The shaft sizes differ mainly in relation to the size of the pump head, 17mm shaft for up to 9mm head and 20mm shaft for 10mm head and over."
[...]
"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."
Perhaps a 6BT - like the 4BT - has a 12MM pump head? Edit: I know you're asking for a 11MM head, but hey, why not shoot for the moon.
Also, maybe some Cummins had 11MM pump heads?
Source:
http://www.vwdiesel.net/forum/index.php?topic=6427.0