ACID leaked from outlet spouts of battery onto the hose which overtime ate away the hose // Also Brake and ABS lite sensor come on and beep>

5 years ago the odometer on my 1990 Audi "90 Quattro 20v" suddenly stopped working when the car had only 49K miles. (Yes, only 49K miles, and I'm the car's original owner.) Anchorage's only Audi dealership said the odometer could not be repaired or replaced on that model. The speedometer works fine (like the rest of the car). Any advice/info on whether my "vintage" car's could be repaired or replaced?

I have a 1988 audi 90 quattro and I'm not sure of the location of the crank sensor. I think it is mounted on the tranny where it mounts up to the engine. The problem is that there are two sensors located there, one is a little bit higher up to the left. Wondering if it is the speed sensor? Anyway I'm not sure how to install the crank sensor. Any help would be greatly appreciated.