Yup, that's exactly it .... what I thought when I read your post #11. Thanks for taking the time to shoot some pics. I had never seen one, installed.
I suppose that you have the correct gears also (T22/T33, vs. stock T21/T34), to have the same ratio - front to rears...?
I know the loggers in my area; all they have is the old style T-136-21 sprag T-cases (from the old gasser-Reo's). So normally they end up with a similar (manual-shift) conversion by eliminating the sprags, but then leaving the stock gears in place. Not perfect, but certainly a lot cheaper... and at least the driver knows he will have front wheel traction when needed.
And if you think about it, that's actually all the Sprag-TC system has to give: enhancing/ improving total traction by assisting the rear wheels - but only when they slip 8% or more - compared to vehicle "ground"-speed.
G.