I had the #7508 (75a: 60a idle and 99a max. As you mentioned, no longer made) for 3 years then it stopped charging at idle. I feel that it should have lasted longer than it did.

Recently I decided to buy another Powermaster unit again and now I am running their new Chrysler Upgrade 165 series alternator. I agree that their customer service is excellent. I was able to speek with a sales rep and an engineer before deciding which unit to purchase.

Note: I have read that you should not exceed 75% of the alternators capacity at idle, or it will get hot and shorten its life. I suggest before you buy, double check your idle amperage needs and add 25% for your "minimum" idle requirement when buying a new unit.