There seems to be a lot of play on my sierra rear caliper pins. Does anyone know what the limit is & if ford sell replacement parts ?

Do you mean the sliding jobbies with rubber boots?

If it's on the sliders, they run through a rubber sleave on the caliper that can be replaced. Sounds like they could be worn.

A call to big red should see fixed http://www.biggred.co.uk

Cheers

Ian