Had a good old look at the GMC steering yesterday because it's got more slack than John Prescotts stomach
The idler arm on the offside is toast , I've just ordered both left and right hand sides delivered tomorrow for £88.05 from USless Automotive.
The have a 35% discount on steering/suspension parts this month, throw in the club discount and they are well cheaper than anywhere else
Don't think it will cure the problem completely, but I'll just work through the many other links/trackrods etc one by one.
Shame they don't do a complete repair kit