Getting the ducts out is a real PITA. Did the 92 come with a cabin air filter?
If so then you know it didn't get past that. To get the smell out, do this about 10 times. Take some Lysol, or Febreeze, or whatever and spray it in the air ducts outside at the bottom of the windsheild. Turn your HVAC to fresh air and on high. That will suck the spray through the vents. But ya still need to get the rodent out and there is alot
of ducts going through the car, alot!!