Transgo & Transco come from the same company. Gil Younger is the man behind the company and was one of the main men in the development of shift improver/valve body kits. His knowledge of the hydraulics in a transmission and how the damn things work are unreal, and a lot of other kits makers just follow what he discovered years ago. To get his kits to work properly they destroy many transmissions until they get the kit to work right.
One kit(the SK-TF) is what in the industry we call a builders kit (small) the other is the big kit used for HD / performance situations. If you're doing this your self and have limited knowledge on transmissions go with the TF-2 Kit. FOLLOW THE INSTRUCTIONS TO THE LETTER. I've seen a lot of valve bodies screwed up and become junk because the installer doesn't follow the instructions or has someone who thinks he's an expert(doesn't work in the transmission industry however) tell him to do things that are all wrong. Unless your helper is a transmission builder be aware of his LACK of knowledge on how a transmission works.
By the way, my 727 has the small kit in it, installed by a transmission builder that understands how they work. With a 245hp smogger engine, it'll bark the tires under WOT going in to 3rd gear, yet under normal driving conditions you never really know a shift kit was in it. When you order your kit, make sure you order the TF-2 kit, not the TFOD-HD2 kit, as the TFOD-HD 2KIT is for the Overdrive series of transmissions.
