Removing the Gearbox last flange

The cheapest propshaft I have been proposed will come with the round differential mounting flange on the gearbox side too. It will certainly look like that:

 
It appears (according to Bob (Robo) on the Haynes and Roadsterbuilders forums), that the Fort Transit MT75 gearbox comes with this kind of flange instead of the 3 bolt flange I have on mine.

(3 bolt flange on my MT75 Gearbox)

(Fort Transit MT75 gearbox)

I might be able get one from Bob, but first, I need to check if it will fit, so I need to check the dimensions of the splined part of the flange on the gearbox shaft. For that I need to remove the flange from my gearbox, but it has a very odd nut and not very accessible.

Thanks to advices from people on the forums (again!), I bought a 30mm offset ring spanner to undo this odd nut, but of course, it is too big.

I first started to grind the flange itself, but that was not the problem.

I
 The problem was due to the shape of the spanner. So I ground it around the ring until it fits.

 Then I made a set up with a steel bar attached to the flange with the original studs to stop it to turn and clamp locking pliers to hold the ring of the spanner on the nut (as the handle of the spanner is not parallel to the ring, the spanner was always slipping on the nut which is not wide), but nor to tight. Then I hammered the spanner until it comes (and used a lot of WD40 too!)

 Finally the nut came out :-)

I pulled the flange out with an extractor. Clean and easy.

It is coming :-)

Now it is out

So here are pictures of the flange, and the last one is with the dims which will allow Bob to check if his round Ford transit flange will fit on my gearbox.

(click to enlarge)