That AX-15 has very wide 1-2, and 2-3 splits, then a lil shorter fourth.
I think you can get an NV3500 from a Jeep, or a GM truck, with a removable bellhouse. It might be easier to find a bellhouse for that, IDK. but the chevy inputs are a lot shorter. IDK if you can swap the Mopar guts into the Chevy case.
The NV has very similar ratios to the AX-15, but the progression is a lil smoother. You will likely want to run 3.91s or so with the NV, compared to 3.55s with the -15.
Here are the ratios I have recorded,there are others;
AX-15
3.83-2.33-1.44-1.00-.79od ......with 3.55s you get
13.60-8.27-5.11-3.55-2.80, splits of
.61-.62-.69-.79
NV3500Dakota
3.49-2.14-1.38-100-.73od ......with 3.91s you get
13.65-8.37-5.40-3.91-2.85, splits of
.61-.645-.725-.73 .....Here you can see the nicer progression, and shorter 4th
