I am building up a 1128 gearbox for my van. It originally had a morris 1100 diff housing and I want to put a mini diff housing on it for the pudding stirrer. What are the things I need to check to do this correctly?

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1963 Morris 850 Smoke Grey
1963 Morris 850 Shadow Blue
1965 Morris Mini Smooth Van
1966 Morris Mini Van
1969 Morris Mini Deluxe Resto
5/72 Clubman Gt

Had this discussion with LINK a number of years ago.
Was told "the diff and gearbox housing are machined together in a matched pair, interchanging parts leads to leaks"
My driveway found out they were 100% correct.

Yes they were bored as a pair but with some care you can mix and match, it has been done successfully many times when needed.
Many 850s got converted to remote way back when, also I've done it when the diff housing was badly cracked in a prang, another when the housing was missing.

Bolt it up with the 2 paper gaskets in, get an inside micrometer or an external one and some engineers' telescopic gauges.
Measure each side at the 12-6 o'clock and 9-3 o'clock positions. Write down the result.
Measure a diff bearing, and compare to the figures above.
This will show how far it is out.
Ideally, you want the 2 housing bores the same as the bearing or .001" smaller. NOT bigger.
If you need to move the diff housing vertically, you can leave out the 2 dowels. They are there to locate the housing during machining, once the housing is bolted up they are not essential to its function.
If it is too large horizontally, the diff housing can be set up in a mill using the figures, and machined to suit.

Have fun.. it's not hard. If you can't get it correct, try another diff housing.

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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.

if you are going to put the pudding stirrer type gearstick then try and match a diff housing that has a small section relieved from the diff housing where the gearstick will be, it is not the end of the world if you do not have one with the relieved section, but I would suggest that you do file that section out, Kev may wish to comment further on this.

As Kev says it can be done if you go about it the correct way

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" A Hundred Years From Now It will not Matter what my Bank Acount Was,
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