I have a 4L65E transmission if i remember correctly. I have had to replace my transmission since i have purchased this truck. But I have always been partial to manual transmission I have read of guys using the NV3500 from 4.3L and 4.8L chevs. But I have heard of guys using NV4500's better for towing and also guys using the 2000-2002 camaro TB manual trannys but my truck is a 4WD and I would still like to tow but gain some fuel milage as well by gaining a gear or two. I have also heard of some other parts to convert the TB trannies to use the 4WD. On a budget, hoping not to spend a whole lot of money. Preferably not have to take it into a shop.