Mixing and matching parts from three not-nice 240s to create one really nice one, I'm confused about differentials. There is the 180 and the 200, and both seem to be shown as standard for the 240. Was one an option, or was found only on later cars? Thanks, Richard McDonel

The 240’s should all be R180s. 
The R200 came in the 280 and most 280zx. There were some zx that did get the R180’s though. I have a chart at home I can share if someone else doesn’t by the time I get home. 
 

(This would be for US spec cars)

Lots of people put the R200 in the 240’s as well as some Subaru R160/R180’s

 

Edited November 28, 20223 yr by Terrapin Z
Added info

Thanks Terrapin, that makes sense to me.

I have old  Black Dragon (remember them?) catalogue that shows the R200 diff as being applicable to models 1970-83.  Maybe that's why they're not in business?

 

 

I bought from Black Dragon long ago. I still have a catalog too. 

The R200 will work in all of the years but did not come in the 240Z from the factory. It is stronger and also heavier. Other changes are needed to make it fit. 

5 hours ago, Richard McDonel said:

Mixing and matching parts from three not-nice 240s

The diffs are probably all the same if they are as they left the factory.  But the mounting hardware could be different.  The very early 240Z's had the differential mounted forward by a small amount, about an inch and a half I think.  It caused vibration so they moved it back.  So the mustache bar and the differential mount are different along with a shorter propeller shaft.

If you post pictures of the three you have and what your goal is perhaps we can assist further. 

@Zed Head detailed out a few of the needed changes that may be required. 

There is different gearing, different half shaft stubs and/or CV axles,  different mounting, different snubbers (strap or RT style) Open / LSD etc......

@Carl Beck website has a good overview of the diffs and ratios ued in 240Z through to the 300Z.

Standard Differentials & Rear Gear Ratio's

https://www.zhome.com/ZCMnL/tech/GearRatios.html

 

Edited November 29, 20223 yr by EuroDat