I appreciate all the help people have given me, but I couldn't figure out some of the programs for port calculations, and box size so I did it the hard way. Please see below.
Total (3) woofers: .75" wood thickness
Box 15"H x 37.5"W x 22"D= 5.766 cubic feet
Port 18"L x 4.5"W (5.25 including the wood added for displacement) x 13.5"H= .74 Cu feet
Subs .12 cu feet each x 3= .36
Total 5.766-.74-.36 = 4.66 tuned @ 35hz
Total (3) woofers: .75" wood thickness
Box 15"H x 37.5"W x 22"D= 5.766 cubic feet
Port 18"L x 4.5"W (5.25 including the wood added for displacement) x 13.5"H= .74 Cu feet
Subs .12 cu feet each x 3= .36
Total 5.766-.74-.36 = 4.66 tuned @ 35hz