I did a study a few years ago on improvised armored vehicles in the United Sates, prior too, during and after World War One. The most elusive information concerned, was the supposedly armored 5 ton Holt tractors used at McCarthy.
I unfortunately have never found very much information on these vehicles. As it states on there CHRONOLOGY, Armored 5 ton Holt Tractors arrived today by rail, built for the Army during the Great War to haul artillery, they were sold in great numbers following the war as surplus.
Ok this is what I have found out so far, Holt did build tractors as we no, to haul artillery, quite a few different ones at that. The U.S.Army used the Holt 45 a 5 ton tractor, which at times was semi-armored. Photos attached.
I never could find out if they were armored in any other way, many, many countless letters and emails went unanswered, to different Historical Societies in Alaska, as well as other states associated with Mr. Nils Tjosevig's and Mr. John Barrett. They were the originators of the McCarthy Settlement.
I have also included another image of an armored car used during the Colorado Coalfield War 1913-1918, it was the "Death Special." This was an improvised armored car built by private detectives using the CFI plant in Pueblo.
I no all of this did not directly answer your question, but its all I have been able to find out.
I had some problems opening your photos (had to try 3 times for some and couldn't open the death car at all.) I've got a 'death car' buried in my files somewhere but its a different strike and a different state! I think that the PIs in this case were Pinkerton. Well here in the UK we think our miners' strike was tough but obviously in the US you take things to a whole new level Getting back to the subject in hand it would seem that the AEF were in the market for an armoured tractor ( one of the roles for the 3 ton tank) so an armoured version of the Holt 5 ton would not seem unreasonable. There's probably a photo encrusted in ice in some remote abandoned Alaskan mining cabin