DD,

they would be referring to the spacer used behind the ring gear to compensate for differences in centres between the low and high ratios.

I was reading somewhere about H165 or H190, and it said the special racing ratios (e.g. high ratios like 4.88) required a spacer to fit in the housing, whereas the more normal ratios did not.

Maybe that's what the H150 spacer is for?

Quote:

Who could you be refering to?.......

The spacer was discussed in Datsun diffs.

The Pitroad page is at PitroadQuote:

This is good news.

I did double check those measurements. I am a trade certified fitter and turner with 20yrs plus experience, not a 14 yr old hairy arse with a school ruler.....Other housings and diff heads may be different but my combination is fine.... The diff head came out of a 84 1.5 ZX Californian Sunny and I have always assumed it was a H150. By the way I was measuring from the inside face of the mounting flange to the centre of the spider gears and all the diffs I have measured the same. I also slapped an axle in the hole with the head on its side to load the spider gear and compared things that way too.

Check the Pitroad site. They sell a spacer ring, so we have a problem. If no spacer is required, then everyone that uses one of theirs will be doing harm to their rear end.

If, instead, a spacer IS required, then you will be doing harm to yours.

I wonder if it would be worth double checking your measurements. If what i believe turns out to be true, then the centerline of the axle will be about 2.5mm further from the gasket face in the H150.

After someone writing somewhere that the H150 diff head needed shimming if used in a 145 diff housing I finally got around to checking it out for myself. Conclusion; no spacer is required , measured 2 145s and my 150 and the critical dimensions are identical. I can now no longer worry about rooting my reasonably rare 3.7:1 diff when the GX fires up soon.