Okay... did some searching, so I know I can retrofit an E-locker from a '98 4Runner into me 2nd gen axle (with some modification), but what I want to know is this:

Can I swap the whole axle? Or will that just mean different mods? Mainly, I'm just lazy and since the truck is my daily driver, I want to minimize downtime.

 

Likely that all the suspension attachment points are different. So you would have to modify all that.

 

4Crawler is correct is saying that the attachment points are different. The housing of your 2nd Gen. can be modified to accept the E-locker probably easier that modifying all of the mounting comfigurations of the new housing. There are several write-ups about this install, just search and you should be able to find the information that you need.