Transmission Speedometer Pinion Gear Assembly 17 18 19 20 OEM 240Z 260Z 280Z 17 T (280zx style housing)

Choose from early or late style.  

*Please read....The details:

So Nissan made 2 different styles of pinion gears that at first appear to be identical but upon closer inspection are different.  The gear and shaft are offset (not centered) in the housing, so that the assembly can only go in one way to make contact with the internal gear to function.  The assembly can be rotated to fit but then the tab/keeper that holds it in place will not line up with the notch in the housing.  So it seems that early cars (all S30) used the style with the retainer tab above the pinion gear and later (mostly 280ZX) place the retainer tab under the pinion gear (see pic).    

So if you have an S30 your options are:

1. use your original housing and swap the internals out with new ones.

2.  purchase the 200-1027 (20T) for the correct housing and then purchase the correct pinion gear for it seperately.  

3.  Purchase the 280ZX style and notch the housing 180 degrees opposite of where the factory did.  

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 Gear Ratios

16 Teeth Gear: 3.36 Ratio
17 Teeth Gear: 3.54 Ratio
18 Teeth Gear: 3.70 Ratio
19 Teeth Gear: 3.90 Ratio
20 Teeth Gear: 4.10 Ratio

Datsun Models & Corresponding Diff Ratios (from factory)
240Z 70-73 MT (3.36) (R180)
240Z 70-73 MT 5spd. (3.90) (R180) - non US
240Z 71-73 Auto (3.54) (R180)

260Z 74 MT (3.36) (R180)
260Z 74 Auto (3.54) (R180)

280Z 75-76 (3.54) (R200)
280Z 77-78 MT (3.54) (R200)
280Z 77-78 Auto (3.54) (R180)

280ZX 79 MT,4 Spd,2 Seater (3.36) (R180)
280ZX 79 MT,5 Spd,2 Seater (3.36) (R180)
280ZX 79 All With Automatic(3.54) (R180)
280ZX 79 MT,4 Spd,4 Seater (3.36) (R200)
280ZX 79 MT,5 Spd,4 Seater (3.70) (R200)
280ZX-GL 79 (3.70) (R200)
280ZX 80 MT,2 Seater (3.54) (R180)
280ZX 80 Automatic 2/4Seat (3.54) (R180)
280ZX 80 MT,4 Seater (3.90) (R200)
280ZX-GL 80 (3.90) (R200)
280ZX 81-83 Automatic all (3.54) (R180)
280ZX 81-83 Turbo - all (3.54) (R200)
280ZX 81-83 MT (3.90) (R200) 

Datsun 510: 1968 (3.70) (R160)
Datsun 510: 1969-1973 (3.90) (R160)