Audi 80 2.8 Tacho stands still

Hello Audianer, my tacho on our 18-year-old Audi unfortunately stopped like a ghost. He has been standing for 3 weeks at 139999Km ?? Just now that I wanted to sell it. What is it like with a swaptacho from the scrap dealer or something? Does it have to be a tacho from a 2.8 or does every tacho just go up to 260? Or does someone have an idea what this new cost? I would need a confirmation from a dealer because of Tacho swap…. r an 18 year old car?? The condition is however SUPER, absolutely no rust!