Correct, Craig Era Ashtons all have three digit stamp codes.
The X size designation was very consistent with Taylor Ashtons (X, XX, XXX and LX, etc.) The more X's, the larger the pipe is. Craig X designations, including LX are very inconsistent. So check the weight, not the size designation if that is important to you.
Taylor nomenclature:
Craig nomenclature:
By example, this LX grade Craig pipe, is 43 grams, which is typically what a XX Taylor pipe would weight.
https://www.ebay.com/itm/Ashton-LX-Old-Church-Bent-Rhmdeian-Pipe-w-Green-Brindle-New-COOPERSARK-N-R/352585028237?hash=item5217b4928d:g:voQAAOSwkAxcVmfH:rk:3:pf:0
This Taylor era LX is 73 grams.
https://www.ebay.com/itm/ASHTON-pipe-pipa-pfeife-Sovreign-LX-silver-cup-silver-ring-rare-smoked-estate/302828748379?hash=item4681fffe5b:g:HVUAAOSwAopbYtBc:rk:41:pf:0