1990 Ford Mustang Voltage RegulatorReview Fitment Notes to Ensure Proper Fit
Motorcraft Voltage Regulator
Part Number: 5477-05372348
Notes: Voltage Regulator -- Without Brush Holder Assembly
Standard Motor Products Voltage Regulator
Part Number: 5477-09100430
Notes: Voltage Regulator
Somehow this regulator slipped through quality control and when I received it it showed signs of having been previously installed, (witness marks on the connections) along with a corner broken off... To their credit, Parts Geek handled it as well as they could by accepting the return and refunding what I paid as well as the cost to ship it back.
So, Good Job Parts Geek! You turned what could have been a very bad experience into a positive one.