Differential identity help

LiamR

Club Member
So I picked up my 2 diffs from my mates garage and when I got them back I realised that they have different input flanges. The squared flange is a 3.54 from my old 1978 280z and the circular one is from my 1978 260z. They are both r200's and after doing the old spin the one flange and count the revolutions of the other... it works out at around 4 so guessing it's a 3.9 diff. I will have to take the cover off to confirm. There is a number on the top of the diff 'S8311 N3100' and googling this just says it's an r200 casing number.

Does anyone know if this diff would have come from a different car (bare in mind the 260z has been off the road since 86) as I see on other forums that it may be a 280zx diff or is it that the 78 260z actually came with a 3.9 diff.

Here are some pics of them...

260z diff
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20230330_201532.jpg
20230330_201545.jpg

280z diff
20230330_201556.jpg
20230330_201602.jpg
 

LiamR

Club Member
I do have a 3.9 z31 diff on my shelving actually. I will have to compare it!! Totally forgot I had it haha! Whoops!
 
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