What a mess. I hate those kinds of messes. Special place in hell for hack owners like that.

Charging is controlled by the computer from 88-up 5.2 and 89-up 5.9 trucks. Usually throws a code 41. The external regulator is a common fix, but its supposed to be on the firewall and grounded case to the firewall, not just dangling on the valve cover.

91 should not have a ballast resistor. Its all ECM controlled ignition.

Should be exactly the same wiring from the last half of 89 5.2/5.9 trucks until 1991 5.2s and 1992 5.9s.

The 88-early 89 trucks used a 60 and 14 pin combo harness plug in at the ECM, whereas late 89 -up trucks used a 60 pin plug at the ECM