Looks like your rear axle has the off-centered differential. To use a marlin t-case setup, you will definitely want to swap the rear axle to a centered differential, or just rebuild the current case with low gears from the other company, and keep your axle (definitely not a cool as a dual case setup, but easier, and probably cheaper).
That pickup is sweet. I wish they made those here
![Crying Rivers :rivers:](https://board.marlincrawler.com/Smileys/marlin/rivers.gif)
. Nice rigs
You could spring-over the BJ and bump up to bigger meats, without too much trouble.