Put a paint or chalk mark on the pinion and the crownwheel, rotate whilst counting em.
You can see the crownwheel looking down into the diff from above.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

22G232 Is the early number for cooper s MkI lay or cluster Gear It was later superseded to 22G1100

_________________
" A Hundred Years From Now It will not Matter what my Bank Acount Was,
The Sort Of House I Lived in, Or The Kind Of Car I drove ... But The World May Be A Better Place
Because I was Once Important In The Life Of A Child"

15/64

My book says Cooper S.

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But he's thriving and striving and hugging the turns.

What's that prove? My S box has a 3.1 ratio (and pot joints) in place of the original 3.44 with Hardy Spicers; it only takes an hour or so.... The other one has a 3.76 with rubber unis...

Umpteen years ago one could not get a replacement S box without trading in one of the same. The valuable bit was the laygear of which there were two types; one stamped ME somethingorother (for a 4 synchro Mk II) and I've forgotten the original number on the other.

The early case was a 333 but unfortunately its still together so I can't look for a laygear label.. 22G1128 is a (maybe not exclusively) Mk II S case number.

Cheers, Ian

Which book?
15/64 is 4.26:1 (same as a Morris 1100), it wasn't native in a Cooper S. But may have been a homologated option for competition use.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Correct! All 22A cooper s boxes had hardy spicers and no rubber unis!

It proves that I counted 15 teeth on the pinion and 64 on the crown wheel and my book says that's a cooper s. Which is exactly what I said, which is ALL I said. Hopefully it proves I can count, read and post my findings.

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But he's thriving and striving and hugging the turns.

Bottom one shown as optional

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But he's thriving and striving and hugging the turns.

That askerisk * there applies to all those ratios below it- std on 1275S was 3.444.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Can you clarify what you're saying her Doc?

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But he's thriving and striving and hugging the turns.

No 1275 Cooper S was sold here with anything but a 3.444.
So, IMO it's incorrect to say a 4.26 diff is an `S one'.
More so considering this book is not an official BMC publication (but it is a damn fine manual for Oz Minis).
That bottom list of ratios shown is just what was available over the counter as spare parts.
However after 40+ years, any box including yours and mine could have any diff in it..

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Wow, that's a brave statement

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1964 998cc Cooper
1971 Mini K x 2
1972 Clubman GT

So the casing points towards it being an S box.

They Laygear points towards it being an S box.

From what I read the diff that is in it looks like an 'option' for an S box.

Is there any other way I can confirm or deny?

My intent is to ensure I am not misrepresenting this thing.

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But he's thriving and striving and hugging the turns.

Alright no Oz built Production S built for the public then.
I'm aware Manton etc could get whatever they wanted...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I would describe this as A three speed Syncro Gearbox With Cooper S MkI gears
Except for final drive, that is not a lie and it should put and end to arguments,

a lot of Police minis ended up with non original cases because the original case may have been damaged (idler gear bearing, silent Cops Etc ) they were repaired with parts from P.A Division and new cases had no serial numbers,
I supplied good second hand cases In the early days to dealers on many ocasions because new cases were not avail at the time,

_________________
" A Hundred Years From Now It will not Matter what my Bank Acount Was,
The Sort Of House I Lived in, Or The Kind Of Car I drove ... But The World May Be A Better Place
Because I was Once Important In The Life Of A Child"