Gus,

The brake light switch doesn't lock the converter - it unlocks it when you put on the brakes. That way, you don't stall the engine if you lock up the rear wheels while in OD.

I like the electrical version becaue the addition of a toggle switch allows you to lock the converter in 2nd or 3rd gear. That way, if you're doing a lot of low RPM driving in one of those gears, you can lock it up and eliminate almost all heat generation. This is a definite advantage if you're driving at an rpm lower than your stall speed.

Don,

I believe that the downshift is controlled by the TV cable. I don't think you'd have to hit the brakes in order to downshift. The alternative is to pull the gearshift handle back from OD to D. The converter would unlock automatically, since the lockup is only in OD (assuming you don't have the additional switch wired in and turned on.)