In the old days we swapped 350s, 400s, C4s, C6s from car to car, as long as you matched for correct engine (v8, v6, 4, etc.) with the only thing needed being maybe a vacuum modulator type swap out and a careful adjustment of the same. And even in a mild performance application, the only thing needed was a simple valve body recalibration kit, that mainly just provided increased overall line pressure and feed to the friction elements. There was no need to customize certain holes in the separator plate to make sure line pressure rise matched the engine torque curve. Following manifold pressure was accurate enough. There are certain instances, as with anything, where the vacuum modulator system is a problem, but for the most part, that is rare. I have never had to resort to a cable on a vacuum modulated trans, although I realize they're available or used to be (B&M). I have had to use simple devices to control the vacuum signal (blown applications). Looking at the cable system in modern transmissions, as Chris has already shown, each and every valve body bore, valve, valve spring and separator plate orifice is specifically matched to the engine it will be mated to in a production vehicle. When you swap a transmission that is so highly calibrated for one specific application, you can run into problems real quick. The easiest way to get around this problem is to install a valve body recalibration kit that will make the transmission a more universal fit. Then the problem arises where sometimes the valve body recalibration kit doesn't quite blend in with a particular OEM calibration and now your either removing the recalibration kit or correcting it. As a trans tech in the 80s, it was common to see revisions or changes to valve body recalibration kits as the manufacturer of the kit attempted to address kit installer's complaints. At one point, when you called tech support about a problem, they wouldn't even answer the phone. In essence, you became their R&D department and when they got tired of hearing the same complaints, they just wouldn't answer the phone. They were to busy adjusting the kit. I can't say for sure this is what was happening, but from my perspective, that is how it appeared. Soon other companies came out with simpler kits that gave more acceptable and consistant results. Again, to go back to the old 3 speeds, I would completely disassemble a 350, 400, C6, TF valve body, throw everything into a basket, run it through a cleaner and assemble them blind folded. That was because you could count on every valve and spring being very close to the same configuration from VB to VB. It was a much simpler time. Back to the thread subject. How many people can identify the size of their torque converter's clutch friction area and the other factors that will determine the life of the TCC under different torque loadings? Why don't we get a listing from everyone of all the different T/Cs that are being used or any that people would like to use.