The Last Chancer, a wooden train built on a jeep platform, is documented at the Helena History Museum. You can view additional pictures at the Museum page. A Last Chance Train still exists, but has been upgraded.
In this early picture taken in 1954 you can see what appears to be a CJ-3B peering out from it’s enclosure.
Here is the Train as of 1957.
The Last Chancer made an appearance in the 1956 issue of Popular Science on page 104:
If that isn’t a classic shot from days gone by, I don’t know what is? All the men in their “suit of clothes.” Too bad liability keeps these scenes left to our history….