Be as cheap to buy a new box from eBay, I got quoted £800 for my gear box to be removed repaired and refit, or if I removed the box and refit it would be £210 for the replacement of 4th synchro, the guys selling the brand new boxes at £350 iv just fitted mine with a new clutch too for £500 but labor charges would be on top of that price, it's a bloody expensive job lol