Triumph Repair: Differential, spitfire 1500, prop shaft

Question
Hi,
I have a '78 Spitfire 1500,  there is play in the diff causing a thumping sensation when accelerating and de-cellerating, the UV's and mountings etc are all sound, its only possible to rotate the prop shaft at input to the diff.  Is this a problem that needs urgent attention and does the collapsible spacer come into the solution.

Answer
Mike,

Is it a single "thump" or does it keep thumping accelerating/decelerating?

Single thump would be diff mounts, engine mounts, and maybe a bit of gear lash.

Continued thumping is more likely a u-joint, either on the axles or on the prop shaft.

The collapsible spacer affects the ring/pinion mesh.   You can get a bit of slap when there's too much play between ring and pinion, but you'll also typically get a noticeable whine.

Does the sound/feeling change when going around corners?   Equally?

Lug nuts all properly torqued?


Cheers,

Jim