AX-15 in a Dart

So I have an AX-15 from a 3.9 Dakota. I am wanting to put it in place of the 4 speed in my 70 Dart Swinger 340.

I heard of it being done, but not sure what needs to be done, I just know something needs cut out?

Can anybody link a thread about it?

Yes, I know the gear ratios aren't perfect, but hey, it's better then the a-833 OD.

It's better then the wide spread auto gears.