To find out what Transmission you have, Go to the inside of your Glove and you will see a White Sticker.....with your Trucks Vin # and a Series of Letter's and Number's.....those are RPO Code's, in short what your Truck came with from the Factory,I was poking around looking at doing to trans upgrades like some of the kits from Oregon performance trans. Was wanting to make sure that my 2008 z71 5.3 is still using the 4L60