a set from a late sierra twin cam

i did the mod as per the msd instructions.

but still did not work i then went to maplins and got the diodes and fitted

them to pin 1 and 3 on the coil packand then off to the green wire on the multi plug at the

back of the clocks and now the rev counter works fine until 3.5k and then it drops down to 0

i think i will just have to get an after market rev counter