You must use a LS1 transmission with a LS1 type engine(unless you pay someone to modify your bell housing to mount to the unique LS1 bolt pattern). The 4L65E Automatic would be the best way to go in my opinion. The shifter location should be checked if you are looking to put the 6 speed in your truck. That or you could use the LT1 instead if you want to do a really simple conversion. The Corvette accessories are the best setup for a truck. I have one for sale in the for sale section here. Going with the LS1 will require a lot of incidental expenses to install including custom mounts, possible cutting of the frame to use the stock a/c location, high pressure fuel pump, custom wiring harness, exhaust, electric fans....the list goes on and on. My suggestion if you aren't married to the idea of converting your older truck would be to sell it and use the money to buy a truck with the 5.3L. It would be cheaper and easier in the long run plus you would get a modern truck with all the newer engineering improvements.