that charger is great for training batteries plus you got 16v/12v charging. if you are only doing 12v the hf1215 is fine, and it charges all batteries, not just AGM
If anyone else needs the rules just pm me your email and I will send a copy. The website is very screwed up lately and will be getting a re do very soon.
i've got an 03 xls same stock alt, mine charged a D3400 up front and D2700 in the back just fine. on roughly 3000rms i had very little voltage drop like 1 volt full tilt. a D6500 is a factory replacment under the hood.
Most of the online ebay stores all come from the same place, so shop around and find the best price.
Also look up lkq or keystone automotive to see if you got a local store, might save money and time on shipping.