I figured this was needed because of the shear number of driveshaft and driveline part related questions I answer for people. All of my knowledge comes from working on Z31's so if I have something wrong, please feel free to correct me and we will make revisions over time!
These are the dimensions of an early 2 seater manual turbo (T5) driveshaft:

All manual transmissions are the same length, so hence all manual driveshafts for two seat cars are also the same length.
Transmissions each have their own unique slip-yoke on the driveshaft, and length for their application:
~Automatic
~NA manual
~Turbo manual (T5)
~87+ turbo manual (90A)
~Automatic, 2+2
~NA Manual, 2+2
In addition, the joints are not the same size in the N/A and turbo (at least manual) shafts; turbos are bigger so you cannot simply swap yokes or diff flanges on the shaft. On a side note I have only seen replacement-type joints listed for the turbo driveshaft's joint sizes, not the NA. It's easy to see from this information that if you want to put a turbo manual transmission in a 2+2 car, you will need to have a standard turbo driveshaft lengthened (re-tubed) or a custom unit made
There are two diff flanges:
Early (rectangle)
Late all 87+ (round/square bolt pattern)
You can swap the differential companion flange on the diff relatively easily with a steering wheel puller. Be sure to re-torque the pinion nut after swapping the flange!
All Z31 differentials will interchange and spline to all Z31 halfshafts; the only notable exception being the SS viscous LSD and half-shafts which are unique.
The half-shafts themselves are only different between turbo and non-turbo models. Aside for having a different type of joint, Nissan also chose to change the style of flange on the outboard flange that the half-shaft bolts on to. This flange is known as the axle stub companion flange because it splines directly onto the axle stub. NA cars have 6 bolts, while turbo have 4:

If you are swapping turbo halfshafts into an NA car, you will need to obtain the correct companion flanges for not only the correct model (turbo/NA) but also the correct year group, as they were changed for the 87-89 cars.
The axle stubs appear to be the weakest link in the otherwise very strong rear end. http://www.modern-motorsports.com makes upgraded units, but they are rather expensive.
These are the dimensions of an early 2 seater manual turbo (T5) driveshaft:

All manual transmissions are the same length, so hence all manual driveshafts for two seat cars are also the same length.
Transmissions each have their own unique slip-yoke on the driveshaft, and length for their application:
~Automatic
~NA manual
~Turbo manual (T5)
~87+ turbo manual (90A)
~Automatic, 2+2
~NA Manual, 2+2
In addition, the joints are not the same size in the N/A and turbo (at least manual) shafts; turbos are bigger so you cannot simply swap yokes or diff flanges on the shaft. On a side note I have only seen replacement-type joints listed for the turbo driveshaft's joint sizes, not the NA. It's easy to see from this information that if you want to put a turbo manual transmission in a 2+2 car, you will need to have a standard turbo driveshaft lengthened (re-tubed) or a custom unit made
There are two diff flanges:
Early (rectangle)
Late all 87+ (round/square bolt pattern)
You can swap the differential companion flange on the diff relatively easily with a steering wheel puller. Be sure to re-torque the pinion nut after swapping the flange!
All Z31 differentials will interchange and spline to all Z31 halfshafts; the only notable exception being the SS viscous LSD and half-shafts which are unique.
The half-shafts themselves are only different between turbo and non-turbo models. Aside for having a different type of joint, Nissan also chose to change the style of flange on the outboard flange that the half-shaft bolts on to. This flange is known as the axle stub companion flange because it splines directly onto the axle stub. NA cars have 6 bolts, while turbo have 4:

If you are swapping turbo halfshafts into an NA car, you will need to obtain the correct companion flanges for not only the correct model (turbo/NA) but also the correct year group, as they were changed for the 87-89 cars.
The axle stubs appear to be the weakest link in the otherwise very strong rear end. http://www.modern-motorsports.com makes upgraded units, but they are rather expensive.
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