• The Ford Motor Co. has produced a number of different types and styles of alternators over the years for their vehicles. These alternator types are defined by the generation. For example, first generation is known as 1G and second generation as 2G. The differences in construction between the 1G and 2G alternators are subtle, but the power output and other factors may make a large difference in performance and durability.
  
  

Case

• One of the major differences between the 1G and 2G alternators are the size of the physical case that the alternator has. Of course, a larger case means better cooling and heat distribution within the alternator, which means that the windings and other sensitive electrical components will be less likely to be damaged by excessive heat. Another difference relative to case size is that the 1G large case alternator will also typically have a larger winding set up than the 2G smaller alternator. Care must be taken when changing alternators, because the physical size of the alternator may require a different mounting bracket when changing to a large case alternator like the 1G.
  
  

Amperage

• Another difference between the 1G and 2G alternators is the total amperage output. Small case 1G alternators are typically 65 amps, while large case 1G alternators produce 100 amps. 2G alternators may produce 100 amps or higher, depending on the specific one you are using. Because the higher amperage output means more available power to operate accessories -- such as sound systems and lights, as well as better charging for the battery -- there may be a functional reason to change from a 1G to a 2G alternator.
  
  

Regulation

• Another major difference between 1G and 2G alternators is where the voltage regulation takes place. The voltage regulator converts the AC or alternating current power generated by the alternator into DC or direct current power used by the vehicle's systems. Most 1G alternators are externally regulated, while most 2G alternators are internally regulated. It is easier to replace a damaged external regulator than a damaged internal regulator, so many swaps go with the externally regulated alternator in case of damage or overcurrent protection.