As yours is the 2.5 Turbo diesel unit it'll be "U25/661".
(From memory "U25/651" was the non-turbo unit....many people think the turbo'd engine was just the non-turbo engine with a turbo bolted on, but it ain't: the specs of a number of the internal components were changed to better handle the extra stresses that the addition of a turbo placed on them).
If you want to double-check: Look over the top of and thus down the back of the engine (as you stand looking into the bonnet). Clean up all the oily crap that'll be there with rags, and you should be able to finally spy the engine type number engraved on that rear face. A little mirror on a stick might help to locate it.
In answer to your other question, again from memory no; not all Fiat engines were fitted with Bosch fuel pumps.
I think there were two types that they used, Bosch and someone elses. But if yours has a Bosch pump and it is buggered, replace with another Bosch (from a breakers etc).
Edited to add: it won't be "8140.27" as that was the IVECO engine, rather than the PSA veriosn, and the IVECO engine didn't start to be fitted into some chassis until 1994.
This may help:
https://en.wikipedia.org/wiki/Fiat_Ducato#1994.E2.80.931999