Just bought a 78 280z 5 speed car. How can I tell if it has an r200? or did they all?

Compare it to your 240's. The R200 is bigger and rounded on the bottom, vs. the squarish look of the R180. If you search this forum for "R200" and "R180" you'll probably find some pictures also. It's probably an R200 unless the car started life as an automatic.

On an R200, the transverse link cross member that you will see by looking at the differential when kneeling behind your car will have a natural bend towards you. If it is completely straight, it's an R180.

MT 280's all came with R200's. Some ratio variations exist depending on configuration.

On an R200, the transverse link cross member that you will see by looking at the differential when kneeling behind your car will have a natural bend towards you. If it is completely straight, it's an R180.

Not true. Only the 70 and 71 were straight. After that they moved the diff back and used the curved link so that they could fix the U-joint angles.

Thanks guys it appears to me to be a 220 which is what I was hopping.

220 volt... cool!

220, 221, whatever it takes.

Also I might be late on theis but if you look into you FSM using you VIN it will tell you 100% what you got for a Diff.

I would say its probably a R200 also.

Not true. Only the 70 and 71 were straight. After that they moved the diff back and used the curved link so that they could fix the U-joint angles.

I stand corrected