I know a guy that may let me take the suspension out from under a Bronco. Will the electronic 4wd switch work or will it have to be mechanical?

 

You'll have to use a transfer case that's compatible with your transmission. Actually, you'll need a 4WD transmission, too. I've never done a 2WD to 4WD conversion, so I don't really know what it takes to convert your transmission, but it seems like it would just be easier to buy a used transmission/transfer case.

I'm not sure which years had electronic shift transfer cases or what transmissions they're compatible with, so hopefully somebody else will chime in here.

 

the 2WD to 4WD swap requires the 4wd output shaft (shorter), the 4wd tail housing (shorter w/ mating bolt pattern), and I think there's a bushing you have to change somewhere. Supposedly can be done without dropping the trans, all in the tailhousing area.

 

Does the tailshaft have to come off of a 42RE which is what I have?

 

This I am not sure. I know the internals are smaller on a 42, but I would like to think that the output shaft and bushings are the same straight across.

 

Can I use a stock transfer case or are they too weak?

 

The NP231D (stock in my truck) is actually pretty strong. I'm still running it with no problems.

 

The thought of doing an sas is also tempting me to do a V8 swap.

 

Also do I need a computer from a 4wd truck or will the 2wd computer work?

 

as long as you use a mechanical transfer case, the computer shouldn't care. If you use an electric one, you can go either way- they should be easily hot-wireable.