Cats in the Redwoods
Couple of views of Caterpillar with Arch -
I think you will enjoy this video below -- one tracklayer shown with 3 stacks - maybe AC?

Hi, ROME K/G.
Those 3-stackers would be A-C Model LO tractors which had both diesel injection and spark ignition running at the same time - up to about 100 horsepower from what I can gather. They are readily distinguishable from the standard model L which had only two stacks..

A-C also made the model K in a KO version which had 2 stacks instead of the standard Model K's one stack. Both O models could run on heavier fuels than their standard K and L counterparts.

Thanks for sharing.

Just my 0.02.

We will never see trees that tall or men that tough again. What great videos!