well if im correct isnt the T56 a 6 speed transmission otherwise they are both pretty good transmissions just depending on what gear ratios you want between the TKO 500 and 600 i believe they have different gear ratios to choose when buying..
Yes, the T-56 is a 6-speed transmission. The Viper T-56 has a .50 overdrive 6th gear, so you can run a 4.11 (4.10 in my 9" differential) drag racing gear (or higher) if you'd like and still be able to cruise on the highway at low rpms.
i have a t-56 and love it but the t-56 weighs a lot more so if your all into racing and weight then go tko 500. both are great and u do not have to change that much. custom cross member $189 from HPM. move speed o cable and lengthin the neutral safety switch wires. also the drive shaft needs to be shortened like 1 1/4 inches