So I recently bought a 2000 Silverado project truck. Its a ECSB Z71 w/ a 5.3l and is bone stock for now. I apologize in advance for all the writing lol.

My two questions are whether to go with a aftermarket torque converter and what if anything I need to upgrade on my trans when rebuilding it?

A friend of my dad's is a retired GM tech who did an excellent job on the trans in my Sierra so I can get pretty much whatever I want done to it. I'm not going crazy with it but it will be taken off road (mostly just mud in FL). Is their anything special I need to replace other than the typical updates? The 4th/Reverse drum is already broken so don't worry about that. Anybody know of a good deal on a updated/strengthened drum btw?

Also I'm trying to decide if I want to rebuild the factory converter or upgrade to a bigger one when I rebuild the trans? The deal breaker on this is how bad it will effect my gas mileage. Something like the Yank 2600 stall looks nice but what will it do to the mileage?

I should also state that there is a 5.3 sitting in my garage waiting to go into the truck later on. I just need to get the money to put it together. Its most likely going to get a cam which would probably make the converter even more promising.

Thanks in advance!!