Hi had my old open diff sent of to Birds Garage as they the only ones who can do the welded diff conversion to be reworked and have a Quaife diff installed. Had car back for around a week and within 20 miles its failed big time with the crown wheel being chewed up and then the pinion bearing failing also giving up on me. The garage who fitted the diff said they only connected the diff so cannot see how it is their fault as oil correctly filed and all they did was connect the final drive to the crank shaft and now Birds are saying that its not their fault as they said they've done over 3000 of these and never has one failed like mine. I've said to both garage and Birds that I will not be paying penny more as I left the car with perfectly good diff and now I have one that doesn't work at all. The chap at Birds (Kevin the managing director) was most unhelpful and I can see this being taken to court as from my point of view they had the crown wheel off and they are the only ones that touched the internals of the diff. Apparently they inspected crown wheel before it was put back together and all was fine. Anyone had similar problems before as thought they were a reputable company but now beginning to question this.