Please forgive me for being naive but what does a shift kit do? I've read previous posts where if I understood correctly it allows D,1,2,OD to shift manually like a stick? If this is so, do you do it when you hear the engine start to rev for that band (rpms are correct for that shift)? Or do they also install something like a clutch as well? Also I hear the Jerry Kit/Fix and or Trans Go shift kits are the way to go for my '98, and to stay away from B&M is this good advice or