RockAuto has reman Delco for $128. New Delphi for $175 and I have used the UNITED IGNITION WIRE for $102. but never checked EST module for timing... there's also MSD for about $175. I don't like A1 Cardone parts even though made in USA they only try to compete with China standards.

I also asked pmkls1 in another thread as he is a GM tech and seems to know how to get the GM replacement.