I have a stock truck and stock rebuilt trans. I am trying to wrap up the install on a TFOD-Diesel kit. I am trying to find out about the 'Later on throttle upshift' part of the kit. I can't find any info. I only use the truck for DD and towing my heavy toyhauler. Any recommendations please? Leave the shift alone or install the heavy spring? I am trying to wrap this up right now. Thanks.