GM HEI

I had two Mallory 4 pin HEI modules purchased from Summit fail within the one year warranty period. Actually the first one failed within the one year warranty, Summit replaced it and the replacement unit also failed within a few months. The engine would shut down, no spark,,,. Had a good heat sink, good ground,,, installed a new genuine GM 4 pin module three years ago, no more problems.
Some aftermarket Hei modules are poorly made. Get a genuine GM module and you will be fine.