On a recent expedition to the Classic 24 hour at Le Mans, we noticed a squeaking noise coming from the rear end of Steve Payne's Interceptor. Investigation when back at home found the Panhard rod mounting bracket on the rear axle had broken off.

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This required re-welding back onto the axle. At the same time, the rubber bushes on the rear of the car were replaced with polyurethane.

Examination of Chris Miller's, and Kerry Moore's cars found that the weld has started to crack on both cars, as well as the one on the replacement 2:88 axle for Kerry's car. It looks to be a common problem, so it's worth checking your car.  

If it's time to replace the rear axle, or your replacing the rear springs, take a look at this excellent article on a MK3 rear end removal. Rear Axle

You should use this chance to check that the breather hole for the axle is not block. If the hole is blocked, it can lead to excessive pressure in the axle, and cause oil to be pushed passed the seal. Marking the position of the hole will help to find it in future. See the picture below.