To give more valuable information we put together a basic way to measure notch placement. Bobby uses a 12x12x12 2x3-inch Sadistic Iron Werks notch for a clean look.

Notch Measurement:
(Tire Height + rear end diameter) / 2 = top of the rear end

Next, using a long straightedge measure from the bottom of the frame to the frame height where the center of the rear end sits. With this info use the equation:

Top of the rear end - stock frame height = the bottom of the notch

So, to recap, let's plug numbers so it makes sense:

26 (tire height) + 4 (rear end diameter) = 30/2 = 15 (top of the rear end)

15 (top of the rear end) - 12 (stock frame height) = 3 (So the bottom of the notch needs to sit 3 inches taller.)