We were looking for my box of late 70s to mid 90s Orange, Gold Race ECU and found some of these. I know there are a few threads on them some say ok to use, some say no. Even saw someone said problems are coated so can't ground them. Seems silly as you would just scrape clean and ground.
With the current quality of new parts use or let them get more dust. Carry as spare in case?
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The only real difference in the Direct Connection/Mopar Performance P3690731 voltage regulator and Chrysler production units is the lack of thermal compensation. Production units are thermally compensated and vary regulation of voltage depending on temperature.
Nominal charging voltage of the charging system is 13.8 volts at 80 degrees Fahrenheit with an operating range of 13.8 to 14.4 volts around that temperature. At lower temperatures, voltage is increased for higher demand of the battery when colder, moving toward a range of 14.3 to 15.3 volts at -20 degrees. Voltage decreases with higher temperatures for lesser demand of the battery when warmer, moving toward a range of 13.3 to 14.0 volts at +140 degrees.
The Direct Connection/Mopar Performance P3690731 voltage regulator does not have this temperature compensation and operates at a constant voltage of 13.8 to 14.0 volts regardless of temperature. Using this on a street car is not a problem itself. However if operated at low temperature extremes, the system may undercharge, or if operated at hot temperature extremes, the system may overcharge, for the respective conditions.
Typically, overcharging with the P3690731 voltage regulator might be more of a possible issue with hot under hood temperatures, than a production regulator. If the regulator is properly installed, connected and grounded with a healthy charging system, it will operate fine otherwise. Carrying as a spare will pose no issues.
The Direct Connection/Mopar Performance P3690732 voltage regulator which is a similar solid state replacement for the 1969 and earlier alternator system voltage regulator also does not have thermal compensation, although the original electro-mechanical units it replaced did not have direct ambient thermal compensation. P3690732 will operate similarly in temperature conditions as the 1970 and later P3690731 voltage regulator with a constant voltage of 13.8 to 14.0 volts.
Chrysler specified the use of the P3690732 voltage regulator on 1969 and earlier alternator systems when upgrading to electronic ignition for a more controlled voltage level with less transients than the electro-mechanical units delivered for the tighter requirement of supply voltage of the electronic control units (ECUs). Alternatively, switching to a 1970 and later alternator and regulator system can be used to the same effect.
Properly installed, connected and grounded with a healthy charging system, the P3690732 will also operate fine, considering the same thermal compensation, and carrying one as a spare will also pose no issues.
Note that the foregoing is based on original design and manufacture of Chrysler voltage regulators. Modern design and manufacture of aftermarket and current replacement units could, and do, vary.
