Who beside gm is using Allison transmissions ford or Chrysler or who?

As far as light duty (Class 1 - 4) trucks go, just General Motors. Ford uses their own transmissions, and Dodge uses the Aisin transmission. If you look into medium- and heavy duty trucks, several manufacturers have the Allison automatic transmissions as an option (for example, you can get them with the Ford F650 and F750), but these are quite different from the transmissions used in GM light duty pickups.