I found a 1984 nissan pickup 2wd, does this have a R180 3.9 or 4.11 in it? I know I found some information on which cars had these diffs (but I cant find it again) and I remember mostly 4x4's. Can anyone give me a list of what cars to find these R180s in? Thanks.

You should be able to look at the diff and realize that it is a straight axle and isn't going to work in your Z. The 4wd's had the R180 in the front end. There is a way that you can tell the gear ratio by reading the VIN number. I'm sure if you searched you could find that info.

Ok, thanks Jon. I found lots of info just nothing mention that specific car. Ill just have to go find a 200sx or a 4x4.

1980 4x4 were all 4.375 R180

1981-82 longbed 4x4 was R180 4.625 (very rare) while the kingcab and standard cab remained 4.375

All 4x4 Nissan trucks 1983-86 were 4.11 ratios.

I believe 3.9 was the rear axel ratio of the 2wd from 1983-86

The 200sx non-turbo from 1984-85 (or so) was R180 4.11 as you probably know

Thats exactly what I needed, thanks BleachZee!

1980 4x4 were all 4.375 R180

1981-82 longbed 4x4 was R180 4.625 (very rare) while the kingcab and standard cab remained 4.375

All 4x4 Nissan trucks 1983-86 were 4.11 ratios.

I believe 3.9 was the rear axel ratio of the 2wd from 1983-86

The 200sx non-turbo from 1984-85 (or so) was R180 4.11 as you probably know

Not quite on the 3.9 in the truck...do a search and you should find some posts with these answeres. I do not remember exact years off hand at the moment though do know that the 3.9 was only in the truck for 6 months before going to the 4.11 (it was the first 1/2 of a year, I just do not recall the year). I have one in storage and next time I'm in the area of the diff I'l see if I can pull the year off it from where the junk yard labeled it.