X in Model Numbers

Someone asked on one post what the X in XM-215 means. An X means it is a non standard wheelbase, all the dumps and I assume the tractors were XM-____

gusc

That's contrary to what I've been told, that the X stands for experimental, as in XM211, then later becoming M211. I've had both and didn't notice any differences.

Joe is deadon about the X standing for experimental. Think back if your old enough or read a history online or in a book. The plane Chuck Yaeger flew to break the sound barrior was the X-1 . Think about it. The Air Corps and later the Air Force couldn't use the letter P as in Prototype because P stood for a "Pursuit" plane so X was the choice. X was the choice to indicate a prototype.


When applied to Military trucks it really means it is a preproduction prototype. For some reason I seem to run into more XM-211's up here in the northeast than any other type of Korean Vintage truck.

X is not only used for vehicles in a limited post prototype production. It is also used for weapons. When I was in the Army I was an armorer. One of my weapons was an xm16e1. This was the same thing as the m16a1 and had the same features. It is not quiet experimental for the trucks we see hear. The prototypes are also designated x but the X vehicles we are talking about above are really more advanced than the prototype stage. They are in a limited production phase for actual field use trials before going into full production when the X designation is dropped.

Thanks for the information everyone. From what it sounds my truck fits the expirimental category. The only thing is that she is an 1954 XM215 with a serial # (on the data plate) of 4281(something like that). Did GMC make any m215s after 54? Or is it possible they just had a short run of dumps in 54 that were modified? So far I haven't heard of any GMC 6x6s after 54 - at least that I remember. When I look at my truck it doesn't look any different than the pictures in the manuals or the few I've seen on the internet except for the following: My truck does have a hardtop which looks old but I don't know if original- it has a flat roof. She also came with a winch originally- too bad its long gone. Could it be the the roof and the winch made it an XM or is their something else that is different? Thanks. Robert

my wrecker was an XM816..