That sounds like a dealership... a ****ty one at that. From my parts experiences the numbers being the same as they is no indication of difference to any great degree. I believe the 04 models boxes had a ****ty latch system (first number) and was adjusted (second number) for the 05 models.
If you plan to add the track rack i may suggest going with the boxes you can get with that system, unless you mean utlitrak (nissan version). the overhead racks for the titan only hould 125 each or 250 together, which isn't a big deal i've had ladders, surfboards, and have sat on them before... i'm not heavy though, only 150. I'm not sure i've they have changed the lids from plastic to diamond plate at any time...
The toolbox itself sits higher then the bed rails and looks a bit goofy to me. SOme have modified the hole on the side so the box sits flush with the rails but then you can't really slide lumber beneath it... hope this helps!
