"X" question

[traindaddy1]

Hi! 

 Can't remember:   On a Postwar boxcar, why were some cars marked with an "X" such as X6454 instead of just 6454? 

(Neighbor says he  thinks it may have something to do with if the car came in a set or was made as an individual item.)

As always, many thanks.

 

[Lehigh Valley 2089]

Probably so one could tell the difference between the product number and the number used to decorate the car. For example: X2458 is the product number while the decoration number is 61100 for a Pennsy double-door boxcar from 1946 to 1948. 

[rtraincollector]

I beleive one ( can't remember if it was the x befor the number or after but those where the cars in the electronic set I'm probably wrong but believe I heard that befor

thinking the ones with the x before the number

[ADCX Rob]

"X" was used to differentiate an item that varied ever so slightly from the root item number.  It could be a difference in trim(railings/no railings, brake wheels/no brake wheels, eg.), a difference in couplers, whether an item was packaged separately or in an outfit tray, or a change in decoration, among other things.

[rtraincollector]

Thanks figured I was wrong but do remember hearing something like that once oh well glad someone knew

[cwburfle]

I don't know of any significance to the "X" prefix.
Thoughts on what's been posted:

X2458 is the product number while the decoration number is 61100 for a Pennsy double-door boxcar from 1946 to 1948. 

The X2458 boxcar also carries the "X2458" markings, on the lower half of the fourth panel from the left.

I beleive one ( can't remember if it was the x befor the number or after but those where the cars in the electronic set

The electronic cars begin with "44". I don't recall an "X" in any of their numbers.

"X" was used to differentiate an item that varied ever so slightly from the root item number.

As far as I know, in this case, the "X" was a suffix, at the end of the number.