stock-laydown (most popular are 767, 4499, or "f")
mod- standup/laydown/p94(it all depends on the motor)
19t-same as mod
P94 are slighly larger brushes. Laydown have a longer face horizontally, standup are longer vertically, although their faces are both the same size.
1989 Mazda Rx7
greddy t04b, megasquirt ecu, PlX wideband, 12x28x3 fmic, 50mm hks clone wg, ssqv bov, Safc, ss oil lines, walbro fuel pump, tubo intake manifolds, ssac exhaust manifold, 3" dp, 550cc primary/720cc secondary injectors, etc.