What is going on underneath my truck

Hey all, I have been experiencing a leak from the axle tube seal in the front differential (passenger). I have replaced it in the past and after doing some inspection today, I noticed a few interesting things.

First of all, when I bought this 1996 Tacoma from the previous owner, I noticed that it did not have manual hubs, despite having no button on the shifter for ADD. After asking the previous owner, he "deleted the manual hubs, it's locked in all the time" because they were annoying or something. A little irritating but okay. So it had manual hubs at one point (in other words, not an ADD diff).

The last time I replaced the axle seal on the passenger side, I also replaced the axle with a non-OEM version (I know). I realized I had been driving for quite a while with a torn boot and wore it out. Didn't pay too much attention when I was making the swap. But today, I looked at the part number on the driver side axle, I noticed it listed 43430-04020 which is the ADD axle part number... It also has the telltale green label, which is for ADD, whereas the blue label is for manual hubs.



After looking in the door jamb, the ID code for the front diff is B03A. Can anyone identify this? As far as I can tell, this corresponds to 8" / 4.10 / 2-pinion open. I thought the fronts were 7.5"



Now all this to say, what axles should be on this thing? Do the ADD axles and the manual hub axles have a different length? Do they have a different diameter on the axle shaft where it meets the differential and could that be contributing to the leak in the front axle seal? I don't want to redo this axle seal a hundred times.

Here's a picture for good measure:

 

All first gen are 7.5hp front

 

The "axle code" on the door sticker is for the rear differential.

 

Roger that. Anyone know any difference between the axle types for the ADD and non-ADD front diff? Or any way to confirm if this is in fact ADD or not

 

ADD and manual locking hubs cv are not interchangeable

 

Okay so presumably, if you used an ADD axle, on a non-ADD diff, but also changed the steering knuckle, that would work? Because that's the way I'm assuming the truck is set up right now. Or would there be an issue mating the ADD axle to the non-ADD diff.