Recently I finished installing an H165 1200 ute diff into my B210 120y, I thought it would be good to make a 'how to' if others wanted to do the same.
1) The h165 ute diff width measures the same as a standard h150 (leaf sprung). You will find the H165 from a vannette is wider than a H165 from a ute. You can use either, you will just have to run skinnier wheels if you use the vannette diff (not always desirable).
2) Relocation of the break line - remove the H165 line and mock up the H150 line onto the housing of the H165 - You fill find the T junction doesn't line up with the existing pedistool. You will need to grind this off and relocate to accept the H150 break line. Weld on securely.
3) Same goes as above for the Handbrake cable. You can make an adapter (as I did) or un stitch and reweld the bracket. Don't use the H165 handbrake as the line is longer than the H150 and wont fit the the existing 120y line. Be sure to re attach with the small clip to hold the rubber part in place!
Yes... you could do this much tidier if you spend more time on it!
4) The big part - The H165 ute diff spring perches will not work with the 120y as they do not allow for the shock absorber to mount. You will need to carefully grind the perches off the H150 and the H165.
Re welding these is where you need to be careful. You will need to measure the angle of the gearbox tailhousing to ground - this should be around 90 degrees, and then match the diff yoke on the same angle in respect to where you weld the perches as it will rotate around on the axle shaft...
You need to be careful to ensure the angles of the tailshaft / diff yoke remain parallel, if not you will experience some unwanted driveshaft vibration which is impossible to remedy.
While doing the above, you will need to ensure the perches are welded on in the right position left to right - All datsun guards seem to be slightly different, so:
1) Tack weld perches with measurements of estimated position (left, right and up/down for correct angles).
2) Check diff yoke angle and compare to tailshaft - make sure these are similar (mines sitting around 2 degrees out and is fine). You want to
make sure the driveshaft ends are parallel to each other.
3) Put the wheels back on and check measurement between tyre and guard is the same on both sides.
4) You may need to complete these steps multiple times to ensure it is correct.
Run some solid ass welds to hold the perches on, I did mine in 10mm strips, left to cool and came back just to ensure I didn't bend the axle housing.
5) Depending how fussy you are (or your WoF inspector) wire wheel, rust kill and paint the diff! They look exactly the same as the standard H150, so unless they see another 120y roll in before your WoF, you shouldn't have an issue.
6) Driveshaft length - There is a lot of conflicting information out there in regard to this. A standard B210 120y Driveshaft measures 1330mm. Due to the H165 having a larger head and longer yoke, the driveshaft will be too long. In my instance I had a shaft shortened to around 1285mm (this is different dependent on yoke type etc). I also tried to swap the H150 diff yoke onto the H165, they swap over fine but you don' gain enough clearance to run a standard shaft.
Have your local shop machine and balance your shaft after you take some accurate measurements, ensuring enough 'play' is left in the slip yoke.
7) When you bolt the diff back in, it might be wise to purchase some M12 U bolts (datsun use M10) just for piece of mind. When you tighten it down, it is a good idea to check the diff is parallel with the front wheels, a quick measure can ensure this and will make sure it doesn't crab down the road.
Don't forget to change over or replace the slave cylinders & brake components, bleed them and then take it for a test!
I found my car to feel more connected to the ground, the diff is slightly heavier so more unsprung weight. A good rear shock upgrade is HQ holden from memory - I have a set installed and they are great for handling, require slight mod to fit.
Enjoy your H165! My a14 was destroying the h150's, so hence the upgrade. Limited information out there for the B210, so hopefully this guide helps someone