don't forget that tube diameter is relative to roll. thickness of the tube is usually matched to the vehicle(ie- sprung weight, weight split)its like a giant swaybar/torsion bar.
mx5 diff would be easy to mount. early ones are easy to get and all imports had lsd( only aussie 1800's had lsd) usually cheap too because mx5 guy like to update to later model torsens(nb series).
what size early camshaft are you after?

My initial choice was to use a Skoda 120 rear frame but
Volvo setup only needs diff to be secured yet can still
use all stock mounting points.
I can use my leaf springs and shockers in original position
and just a subframe for the diff centre.

The Volvo 360GLT is around 970kg so shortening this setup
is going to make it stiffer more for a 1300kg narrow car :)
Id like an alloy beam like on some ford SUVs but out of
reach due to described limits.
I like the MX5 diff and might use the centre still if
I cant nab an alloy centre with lsd from pick a tart.

Stock camshaft is preferred will suit supercharing better

I have a standard early a series cam for sale. only problem is it's brand new.

PM me a price Bob.

Miata diff is cheap with obx new centre from ebay.
However prefer suzuki xl7 all alloy with clutch plates.

second hanf for 75usd buy it now
http://cgi.ebay.com/ebaymotors/LSD-Mi ... ories&hash=item5199875ea3

brand new obx 280usd
http://cgi.ebay.com/ebaymotors/OBX-He ... ories&hash=item2566cd40ff

1st one not sure it will fit.

obx seems ok (is obx a good brand???)

Some fundamentals need to be understood here.

Firstly, A De Dion rear end is not an IRS since the hubs are joined by the de dion tube. The fact that you have a transaxle and half shafts does not make it an IRS.

Only advantage , albeit quite significant, is that you reduce the unsprung weight by have the differential attached to the body and not the wheels.

Secondly, Camber is fixed, there is no adjustment. It is built in. If you look carefully at the flanges to which the hubs bolt to they are pressed at an angle and thus have built in negative camber of a few degrees from the factory. Yes you can cut them off and re-attach them at some other angle if you wish.

I'm not sure why you label this transaxle as weak and rubbish. The 360 GLT runs a 2 litre motor. You are installing this in a Dato 1000. Of course depending on what you are doing with your engine and how you propose to use is will impact on the longevity of this axle or any other for that matter.

Perhaps go over to the Volvo 360 site and seek comments specific to your application. http://www.volvo300mania.com/forum-uk/

I have mentioned camber is fixed due to the hubs
and that we can get more camber with cut/welding.
However w/ good engineering, it can be made easier
to adjust using a hinging setup with stepped holes
and securing pins to suit different conditions.

The axles are independent so although not full IRS
its still is to a point and superior to live axle
hence my interest in this "semi IRS setup"

Ive trolled through that site many years ago searching
for an easy disc brake setup but they mainly use Euro
VW parts that here is locally unwise to use. Also read
that many "300" fans state it is the only weak link to
an otherwise bulletproof DAF/Volvo car.

Earlier in this thread if you had a chance to read it you
would have found that the rear "transaxle" was never part
of the plan as it eliminates the simplicity as they are
rubbish for parts, lsd, operation and packaging etc.

Im not sure on quality of OBX for miata centre either
I guess that the miata forums would have this info.
The all alloy Suzuki XL7 diff is my aim atm.

Kinda what i said on the last page, with no detail, not IRS at all, yes the axles can move indoard due to the centre being fixed to the body, would have to be careful changing the flange angles to adjust wheel alignement if the half shafts have Uni's, CV's you might get away with a little more..

Mike acknowledgement is deserved! :)
Audi diff in the radar atm