270a Unit is 200a at idle, 280+ at 1800+ RPM.
390A unit is 190+a at idle, 400+a at 1800+ RPM.
These units bolt onto the chrysler 2.7-3.5-5.7-6.1L Engines with the T mount configuration. the 5.7L and 6.1L do require washers to space the alternator higher up on the bracket. The 2.7 and 3.5L requires no modifications. They will be plug and play PCM controlled like stock.
The 270a units will come with a stock diameter type pulley so you do not need to change the belt length.