[Legbreaker]

Thanks for the initial numbers Olefin, however there's some MASSIVE holes in your argument.

Firstly, both editions of the US Vehicle Guide only state number of tanks. The RDF Sourcebook lists numbers of AFVs.
The definition of an AFV, or as they are properly known, Armoured Fighting Vehicle is basically any vehicle with a weapon and armour of some kind. Technically, an armoured Humvee is considered an AFV - a far cry from being a tank...
Note also that OPORD OMEGA specifically states in the "mission" section that "Vehicles and heavy equipment will be transferred to FRG prior to departure."
Therefore, there is absolutely no inconsistency between the two books to justify transfer of tanks from Europe to the Middle East, and canon clearly states this was not to happen.

Secondly, the US Vehicle Guide only shows combat aircraft - those specifically tasked with direct combat roles such as the AH-64 Apache.
The RDF Sourcebook includes transport aircraft such as the UH-60 Blackhawk and also shows the OH-58 Kiowa, which is nothing more than a scout and observation helicopter. Both of these latter two can be armed, but they cannot possibly be described as an attack helicopter.
We can therefore apply the same tank/AFV logic.

The next point is even more obvious.
According to page 17 of the RDF Sourcebook, General MacLean "made it known to all the troops of CENTCOM that if they wished to return to America, arrangements would be made to get them there". Now admittedly only "a few hundred wanted to go home," but that is just the start of accounting for the allocation of the 6,000 bodies from Europe.

The US Vehicle Guide lists manpower as of the 01JUL00, six months before the RDF Sourcebook. According to the RDF Sourcebook, US units (specifically the 24th ID) were engaged in offensive operations after this date and could be expected to suffer losses from the 2,000 of 01JUL00. These losses could be just a handful, but since the smaller Iranian 44th Infantry Brigade replaced them after only a few months, and the 44th isn't included in the OOB of 01JAN01 (potentially destroyed with survivors reallocated), it's very possible the 24th ID suffered badly. The 24th is therefore a probable recipient for a large portion of Army replacements (more than the 2,000 difference between July and January).

Furthermore, there has been no attention given to anything besides the US Army.
What about reinforcements for the Navy, or the Air Force? Ignoring shore based personnel and looking only at the the ships in TF76, they require crews totalling 3,828 officers and men. Are we to believe that years of combat have left those crew numbers unchanged? Shouldn't we also apply a similar ratio of losses as faced by ground forces which is roughly 70-80%? Doesn't the Last Sub trilogy bear out the belief that replacements have been few and far between, even though Omega arrived approximately five weeks earlier? (only a skeleton crew could be found from all the Milgov controlled areas to crew the Corpus Christi).
Applying a modest 66% loss to the Naval forces (which is much lower than I'd honestly believe) that means they need 2,500 warm bodies (which may explain why there were few suitable naval specialists to be found in the US in January 2001).

And what about the Air Force? According to the RDF Sourcebook, Aviation units have a manpower on 01JAN01 of 3,050 - note some of the listed units in the books did not have a manpower number attached. How many of them are replacements from Europe?

Given the last major fleet in being was destroyed off the coast of Norway way back in 1997, it's very possible that a significant proportion of the 6,000 are survivors of those actions. With the lack of aviation fuel, parts and ammo in Europe, it's also likely a sizeable number of pilots and ground crew volunteered to go to the Middle East just for the chance to fly or work on aircraft again.

It is my belief that roughly one third of the 6,000 probably came from navy or air force origins.

Where the RDF Sourcebook shows an increase in AFVs which cannot be explained by any of the above, there is another solutions - captured vehicles. We already know enemy vehicles were used by both sides, and we know the US 2nd Marines actually increased their numbers in both manpower and tanks - what's to say a small (company sized) Pact mechanised unit wasn't wiped out/routed and their vehicles captured? We are after all only talking about a handful of AFVs (which as mentioned earlier could be nothing more than scout cars).