Nissan didn't install the R180 upside down in the trucks. They just turned it around so that the cover faced the front of the truck and made the diff drive on the "coast" side of the gears as John Coffey said earlier. It's weaker that way, but it is in the front end, so it doesn't take as much punishment. Flipping it upside down would leave the pinion several inches above the oil, which wouldn't last very long at all.

Reasons to stay with the R180:

1. Lighter

2. Fits with no mods

3. Can be found in lower ratios from the 200SX, but needs a slight mod described in the hybrid z FAQ post

Reasons to go with R200:

1. Stronger

2. Can handle V8 power

3. 87-89 300ZXT came with LSD

4. Very easy to find 3.90 gears from 280ZX

The "what parts do I need" question is answered in that FAQ that Mat linked to as well.

I stand corrected, I had been told previously that it was flipped upside down. Sorry for any confusion.

I too have the 79' 280ZX 5-speed and after that, I installed the 4:11 R200 diff out of an 83' ZX. I get great low end and also get 28MPG on the Highway!!!

But I'd listen to Jmortensen If I were you, He is the $^!# when it comes to Z diffs.

jm2cw

Dave.

One thing that hasn't been mentioned is that you need to replace the transverse link with one that is curved . One from a '72 on. that is if you go with a R-200

and its very fun to change...i just did mine =]