I have a 5.3 and I dont think I have a tranny cooler. How hard would it be to install one from scratch, i.e. not replacing a factory one? Thanks

 

If you have a tranny cooler, it will be easily visible behind the grill right in the center. Power steering cooler (if equipped) is also visible on the driver side. If you want to install one from scratch, just order the kit and it will walk you through it in detail. Basically you just disconnect (unscrew) the return fluid line coming out of your radiator (the line on the bottom) and use the supplied hardware and hose to create a new line to the cooler from the radiator. From the cooler create a line back to the return hose you previously disconnected from the radiator. Mount the cooler in front of the radiator or condenser and your done. Again, very well explained with illustrations in the B&M kit.
You may want to use teflon tape on the threads of the brass fittings. Did a f-body install today and had a leak from the radiator...teflon tape fixed it.