Yes Marlin can covert a t-case to 23 spline, You have the right case in the front I believe,so all you need is the adapter and a gear driven T-case for the rear, just like the one that is in it now
![Thumbs Up :thumbs:](https://board.marlincrawler.com/Smileys/marlin/thumbs.gif)
And I think it's better to have the gears in the rear case, so you not sending that extra torq throuhg that other case when you don't need too.