I have a 1990 K2500 that is my tow rig. It has a new engine and rebuilt transmission from a previous owner. It runs good but the only problems is it shifts at 2800-3000 rpm even at WOT. It isn't a problem when empty but when pulling a heavy load I could use some more power to the pavement. It came with a 700R4 that had died and the previous owner swapped in this TH400. I already checked the kickdown switch and adjusted the modulator so I know they are good. I did unhook the vacuum from the modulator to check it and was rewarded with a tire chirping 4400 rpm 1-2 shift. I know this 350 TBI engine makes peak torque at 2800 rpm and hp at 4000 and has a 4500 rpm redline. My half throttle shifts are at 1500-2000 rpm. So I think adjusting the governor is my best bet. The problem I am having is all the info I am finding on this topic seems to be drag racing related. I get that it takes a bit of trail and error to dial it in so I don't want to grind away some metal and find that I have a 7000 rpm shift point. I know I can get a kit for $50 to adjust the governor and the lighter weights raise the shift points. But it only has the inner weights and springs. What do the outer weights and springs control? How do I adjust the part throttle shifts up? I want my half throttle shifts to be at 2500-2800 rpm and my full throttle shifts at 4200-4400 rpm. Should I just buy a new governor? Or do they all use the same governor regardless if it was a diesel or sports car? Can someone please point to a good source of information? I ask the same question over on Pirate with very little response.