I used toggle switches in my CrewCab
Flipped them at 40 & 50 mph
Took a 155K transmission & shifted it like that for another 50+K before it finally quit

You can hunt all the stuff at the JY to build their lockup kit it involves pulling the pans on a GM 350 lockup & a 700R4 for the pressure switches & the vacuum switches can come from a GM with a lockup tranny