<See additional post below -- my mind was confusing simply dropping the diff with drop bracketry for the whole a-arm assembly, even though I knew damn well we weren't talking about dropping the whole assembly... So MOST of this post would be more of a reference to a Chevy IFS style drop bracketry lift...>

This picture shows the reason the drop diff hasn't been used on the 98+ Rodeo/Amigo/RS yet -- and it's not the CV's. It's those other sets of bellows in the pic, the ones attached to the Rack & Pinion steering, outside of the photo to the right. This particular Rack & Pinion has a serious weakness if allowed to droop too far to the extremes of travel. Several people running 33's and above have bent their droop stops (very weak on the 98+ trucks) and subsequently blown their rack. If I recall correctly, it's $188 from Isuzu (St. Charles I believe) but I could be wrong. I never replaced mine but it was leaking and about to go when I got rid of the truck. Corbin Cowan replaced his several times. Tho I can't remember exactly who, I know several others had to replace theirs.

That being said, dropping the diff would allow for additional downtravel, beyond the scope of the original design for the steering rack, and therefore would likely blow out the rack. Of course, the rack could be dropped an equivalent amount, however, this is not a particularly easy task. The rack mounts ABOVE the frame rails, so the only way to drop it would be to put it UNDER the frame, which of course leads to a dizzying amount of additional fabrication. Not to mention the fact that the frame in that area is somewhere around 4 inches tall, so it would be a drop of 4 inches. You'd have to match that with a diff drop of 4 inches, otherwise the uptravel would likely blow out the steering rack as well.

As you can see this could be done with the right amount of perseverance and fabrication skills, but by the time you did all this, wouldn't it be easier to just swap in a solid axle? If you have the fabrication skills to do all of the above with the rack, swapping in a solid axle with coilovers and full hydraulic steering would be like child's play. <img src="/forums/images/graemlins/wink.gif" alt="" />

Now, that being said, if you could figure out the extreme lower limit of the steering rack, you could drop the diff only that much... Or you could limit the droop to a point that wouldn't harm the rack, but the whole point of this is to increase downtravel, right? Probably the easiest option (but one of the more expensive) would be for someone to machine up replacement tie-rods for the steering rack which would be longer... Problem is, Isuzu calls this a non-serviceable part, so there's not a good chance you'd find anyone willing to take this thing apart, design, tool, and machine up the parts, and put it back together without any problems... But then again, money makes the world go round, and some people love a challenge. <img src="/forums/images/graemlins/wink.gif" alt="" />

Anyway, just wanted to point out probably the most important reason not to drop the diff on the 98+... And point out a bunch of options for those people more ambitious than me -- when you make it, I'll buy it...

<img src="/forums/images/graemlins/smile.gif" alt="" />

-Chris