The 2x2 cuts for a 4 tub rack instead of 6 tubs are:
7 x 44" (legs & back brace)
8 x 21.5"
12 x 24"
8 x 22" (rails)
4 x 10" (scrap for spacing) pieces of 2x2.
4 x 12" (bucket stand legs)
12" x 12" square of plywood