Knightprobe

I have a 1984 firebird with a 2.8 liter v6 with carburetor and I recently changed the ECM and prom because the guy I bought The car from had the wrong prom in the car because I was getting a code 51, anyway as soon as I started the car up after installing correct new ECM and prom the check engine light came on immediatley and I am getting a code 41 which is a no distributer refrence pulse signal, If I check the codes with the car running I get code 12 and code 41 does anybody know what would cause this code to come up, I checked all the wiring at the distriburter and it looks ok, do I need to replace the distributer?