Thanks guys, made a smile reading your posts

Car just after the diff pin falling out:

So.. lots has happened since the car broke again.
Bought x-pin diff:

Cut up an old toolbox and attached it to the dash to hold my gauges temporarily until I can get something made in aluminium.

Ouch.. less than 3 miles old:

Oh.. and did this..AGAIN:

I've got the x-pin installed now and it looks and feels solid as fooook. There's no play at all like the old diff which should make it really nice to drive. I found that the shims they give you make the diff totally lock up once you start to torque the crown wheel down so I had to re-use the old shims which seems to work a treat.
The engine is currently sat in the bay waiting to be reconnected, so hoping to have a chance to do that soon and it should be back finally!