I donít know if you remember me consulting you on tach problems on my vette. Any way itís an 81. I rebuilt the tach and hooked it directly to the signal from the PCM It works but I suspect that it off a bit. Iím very happy that the tachometer moves again. I just need to get my hands on a programmer and check if the PCM is set on 4 or 8 cyl and play with it.