1979 Tach not accurate

Hi Guys,

My 79 has a tachometer issue. The RPM's seem to be anywhere from
1500-2000 off. Recently my warehouse got flooded. The vette was in
the warehouse and the water (fresh water)got up to just above the door
pulls. Thankfully the dashboard wasn't under water. I am currently
replacing all the affected things. Carpets, seat cushions, removed
all the console pieces and cleaned all connections switches etc...
however I now have this tach problem. is there anything in the lower
part of the car that could have gotten wet that can cause this? I'm
at a loss where to go with this. The last time I drove it about 2
years ago, it was working fine.

Greg