Is there any diffrence between the 120y diff and the 1200 diff????

Yes. The 1200 uses the H145 diferential, while the 120Y uses the H150.
Both of these share the same diff gasket & will interchange within the rear axle housings, however the distance from the gasket face to the centerline of the axle is said to be greater, about 2.5mm greater, than the H145.

If this is true, then you would need to space the H150 diff out from the axle housing by the amount that they are diferent to avoid problems.

Using a H145 diff in the later 120Y rear axle housing is not a proposition. From July 1976, Australian built 120Y's used a Borg Warner rear axle assembly which is completely diferent.

Its just a bloke has one 4 sale nearby. And with the A15 in my ute, with the stock 1200 diff and 4 speed gearbox, sittin on the highway doin 120km and uncomfortably sittin on 5 and a half grand. Its a bit annoying. What woul be a wise thing 2 do her in my situation. I was told 2 get a standrad 1200 coupe diff????

i was just lookin in the tech section, theres a part that says the newer 1200 utes came with the H165 diff. what do they clasify as a newer ute. Mine is a 1981 ute, is it classified as newer???What im mainly intereste dis if its worth gettin the diff from this 120y or not???

i was just lookin in the tech section, theres a part that says the newer 1200 utes came with the H165 diff. what do they clasify as a newer ute. Mine is a 1981 ute, is it classified as newer???What im mainly interested in is if its worth gettin the diff from this 120y or not???

Ahhhh, thats diferent. You didn't say 'ute' before

Datsun 1200 utes used the H165 diferential with a 4.11 to 1 ratio. All series 1 & 2 Bluebirds with auto or five speed along with Stanza's used the H165 with a 3.9 to 1 ratio. These will interchange & give you a bit better driveability. The original tyre diameter was 552mm from memory, but if you use a tyre of larger diameter on the rear, it will also increase overall gearing. If you go to the 3.9 diff, then use the speedo drive pinion from a 1200 or 120Y sedan to help correct the speedo reading. This is assuming that you are using the original 56A gearbox.

If your ute has the H165 diff, which it should, then forget the 120Y diff.
1981 would be considered so late a model that it should be still under warranty.

Yeah, stick with the H165, the H145 and theH150 don't have the greatest of longevity with drivers <25. I'm still hunting for a 3.9:1 bluey diff centre myself.