Two important points. Firstly, under the US Army's nomenclature system, any system that is determined not to have been specifically modified for US Army use does not have to receive an Army Type Designator, instead using its commercial designation. As COTS purchases it appears to have been decided that MRAP/RCV family vehicles did not warrant an Army Type Designator. This same sort of reasoning generally applies to other service designation systems.

Secondly, some MRAP vehicles have received designations:

- Mine Resistant Vehicle: BAE Tactical Vehicle Systems, Category I, XM1220 (Caiman Light)
- Mine Resistant Vehicle: BAE Tactical Vehicle Systems, Category I, XM1230 w/ EFP Armor (Caiman Plus)
- Mine Resistant Vehicle: BAE Tactical Vehicle Systems, Category II, XM1248 w/ EFP Armor (Caiman)

What's interesting here is the company name in the extended nomenclature. Note also that the Caiman family has significant commonality with the US Army's FMTV family.

The three variants of the Panther MMPV (part of the RCV family, not the MRAP family; different program, different funding) have also received designations, but I only know the Army Type Designator and not the full nomenclature:

- XM1226 (Engineer variant)
- XM1227 (EOD variant)
- XM1229 (Intelligence variant w/ Prophet system)

I assume these vehicles are also in the Mine Resistant Vehicle category, but having some experience with US Army designations and nomenclature I wouldn't bet any real money on it heh.

The biggest problem here is that "MRAP" has become a generic term in common usage, when it in fact refers to a specific program managed by the Joint Program Office MRAP (JPO MRAP). Other vehicles of identical types are managed by the Army's Project Managed Assured Mobility Systems (PM AMS), and are part of the Route Clearance Vehicle (RCV) family (which also includes the Husky. The different budgets mean that in many cases the vehicle nomenclature is different (RG-33L or Panther MMPV for instance). Only the Panther MMPVs have XM numbers. The RG-33s managed by JPO MRAP are still just RG-33s, though JPO MRAP plans to pass all responsibility for the RG-33 off on PM AMS in the future, which would allow them to cut back on the number vehicles they need to buy. It appears they also want to pass the Buffalo off onto PM AMS entirely as well, if they haven't already. JPO MRAP hopes to eventually whittle down the models its responsible for to the M-ATV, RG-31, MaxxPro, and Caiman.

PM AMS effectively manages what started out as the Ground Standoff Mine Detection System (GSTAMIDS) in the 1990s, which was the reason for the initial investigation of what we'd now call "MRAP-type vehicles" before IEDs became threat number one to US forces.

Also, while MRAPs aren't in the TOE or in any specific MTOE, and are assigned as Theater Provided Equipment for deploying units, RCVs should be part of the Engineer Company, Route Clearance TOE, whatever that is. These units comprise the majority of units slated to retain these type of vehicles in the future. The Army otherwise plans to store "BCT Packages" in pre-positioned stocks to be used as Theater Provided Equipment should the need arise in the future and otherwise divest the balance of vehicles.

Any particular reason they are not retaining the Cougar/JERRV family? Were they the smallest number ordered?

Actually the vehicles are not strictly COTS, but were developed under the Rapid Acuisition/Rapid Equipping initiative and were not done as a "Program of Record". (Had it been a normal Program of Record, they'd still be aruging over requirements, and still be in the Technology Development Phase)