There were a total of either 3 or 4 crates in the GMC Two Unit Pack. The 353 used 3, those being (1) Chassis box, (2) Cab box, (3) Axle box. The 352 used a 4th box which was the Tire Carrier and Fuel Tank box.
If cargo bodies were supplied they came in an additional pack.
Information is from 'ASSEMBLY OPERATIONS, GMC Trucks 6x4 and 6x6," Two Unit Pack". 1942 Form X-4226
Technically there are 4 boxes: Cab Chassis Axle Cargo body bundle.
These are listed on page 4 of the TUP assembly operations manual. Page 3 lists only 3 crates... but a CCKW without a bed has little cargo carrying capacity.
For a 352 the transverse fuel tanks are in the axle crate, whereas the 353 tanks are in the cab crate (IIRC).
If you watch the two videos about field assembly of CCKWs in the other forums you can see the separate body crates on the lines.
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