Jim Hearne originally provided this information via the Google Group and it has been slightly edited to work as a faq. The post was in relation to converting a Quantum 2+2 from a CVH engine to Zetec power. This conversion has been completed successfully many time by members, but there are a few things to look out for, especially ensuring that the ECU is matched to other sensors and components, such as the MAF and injectors. This faq provides useful information about the different ECU codes Ford use.
DEWY, DEEP and DESK are all Zetec 2.0L ECUs
BLIP and BLOB are Zetec 1.8L Mondeo ECUs without PATS
BLOB is part number 93BB-12A650-BB, BLIP is part number 93BB-12A650-BC
Since it's only the very last letter that is different it will be a compatible part, it's just BLIP is a slightly later version.
For the pre PATS Mondeo if the 4 letter code start with;
A it's for the 1.6,
B is for the 1.8, options are BLIP or BLOB
C is for the 1.8 Auto,
D is for the 2.0, options are DEWY, DEEP or DESK
E is for the 2.0 Auto.
Don't bother with ECUs from an automatic gearbox car, since they have external EDIS and the ECU runs the auto box as well.