You might be speaking of the TurboBuicks.com 200 amp alternator upgrade kit that is about to be released. This is a kit that I put together that replaces (3) components in the Buick GN's original 120amp alternator bringing it to a 200amp rating.
One Upgraded Stator with more/thicker windings.
One Brand New rear bearing (non-serviceable)
One Brand New Brush Kit with holder
One New Heavy Duty Internal Regulator
The installation of these pieces take about 10 minutes once the alternator is on the bench. The process is easy and you'll be back charging in no time. Initial testing shows less voltage drop when using a lot of accessories, faster charging of the battery ect. I have used an upgraded alternator on my Buick for quite some time now as the test mule. It doesn't seem to run any warmer then a regular alternator and looks completely factory from the outside.
I will be offering these kits to fund the TurboBuicks.com website once I get a few in stock and get some installation instructions posted here on the website. Price will be ~$75 and will be offered here.
I just spoke with my alternator rebuilder yesterday about doing this. He said it only works at a higher RPM range and actually lowers the near idle charging rate. (I'm not knocking anyone just telling his advice on the matter) A late model Riv used a 140a CS144 alternator which might work better than the stock alt. A stock TR alternator charges at 60a at 1000 rpm. To do it correctly would be installing a much larger alternator (physical size) that would charge more at all rpms. I'm going to compare mine to the Riv alt and see if the charging rate is better. I'll post my results so you can decide on which way to change the rate of charge. Gene