Hmmmff... Took it a run at the weekend.
Diff seems VERY noisy. It locks up fine, but it sounds like... a flintstone car? Like.. stone rolling on stone? Like a pestle and mortar? Very audible inside the car and its deffo the diff. Stripped the rear brakes off it as at first I thought it was them and the sound remains.
Any suggestions before I remove it AGAIN. :( Could it just need a good run / few heat cycles?