Yep, as Dodgeman said above, not using the spacer will cause the rear suspension to have a small amount of toe in along with the attendant slight misalignment of the axle splines in the differential carrier and wheel bearings. Doing some quick calculations it looks like the toe in caused by moving the center of the axles rearward by 2.5mm assuming 558mm (22") length between the differential and wheel bearing would come out to be just under .25 degrees.

Back in the late '70's I saw a Chevy Camero at PIR (Portland International Raceway) that looked like it has negative camber on the rear wheels, a interesting trick as the Camero had a straight axle like the 1200's do. Talking to the team they had used a porta-power to actually bend the axle housing down in the middle enough to get about 3/4 degree negative camber on the rear wheels. Said the axle splines held up for several races before they replaced them. This was in a car that was putting close to 500HP on the ground.

How much will a quarter of a degree of toe in will effect the handling? I don't know...

Quote:
The transverse centerline of the H150 differential is [allegdly] 2.5mm further back from the mounting flange than the H145 is.

Now that's not a lot & there is enough movement in even a new wheel bearing to allow the axles to engage the drive splines in the side gears without binding [apparently]

So it all fits & works, but in reality, the rear wheels now have a tiny amount of toe-in & the bearing balls are not running true in their races, so it would be fair to say that tyre wear would be increased by a small amount & the service life of the axle bearings would [theoretically] be decreased.
Does this tiny amount of toe-in affect the way the car drives & handles?
I don't know, ...... what I do know is that those who think twice & act once will either add the spacer, or leave it out for reasons that they can quantify, not because I, or anybody else, said so.

Alloy is easier to cut & does the same job as steel, & the second gasket [one each side of a spacer] is .5mm thick [I measured one] & the combination of the spacer & gasket gives you the 2.5mm.

I plan to use a spacer when I fit my H160 diff into my KB10 rear axle housing because I have great faith in Datsun engineers.
They modified the H150 rear axle housing design to move that gasket face forward & this would have cost the company time, effort, & money, .... & they don't do these things unless they believe it was necessary. These clever little men would know far more about these things than I ever will, so if it's good enough for them .........................

Well, that's the best excuse I can think of.

Thanks for all the info.I do have the tailshaft it is out of the 120Y sedan so I hope I won't have a length issue. I have never had a length issue with my shaft before. Iused to work for Driveline Services so I could ajust my shaft to any length I needed, we did it all the time. As far as our local fitter is concerned I have seen his work (Bad! Very Bad!!) I am going to check out a bloke in Roma but I think I'll get one from a 1200. com trusted source. Thanks again guys, It's all good.

a really good mate of mine has a 150 in his 145 housing (kb110) and when i asked him weather he used a 2mm spacer, he told me it wasnt neccesary, use two gaskets if you want etc etc.
I guess you only really know by doing.

Just make sure you've got the H150 tailshaft as well.

Pitroad sell them but I think your tractor fitters would be able to do the job just fine, its just a 2mm piece of steel cut the same shape as your gasket, add a gasket either side.

Hi All,
My next job slated for the "Frog" is to fit the H150 over the hols. I know I'll need a 2mm spacer. What I dont know is where I can get a well made one. I can't trust it to any of the hillbilly tractor fitters we have around here so I figure one of you would know who and where. Also is there anything else I should know before I start.
Thanks