You already have blocks in the back, so don't stack them. Spacers are not made for your model, since you have torsion bars not coils. You can crank your torsion bars for 1-2" of lift. If you are looking for a budget lift, other than mentioned above, the next cheapest thing is a body lift.
Sold:2004 XLT 4x2 Ext. Cab. 3.0 Mods: 3" spindle, AAL, shackle, 32x11.5 on 15x8s, billet grille, clear corners, flow 40 dumped, line-x, CB/PA, traction bars, lil sound system, auto up down windows
Sold:2005 XLT 4x4 Ext. Cab. 4.0 Mods: ProComp lights w/ HID swap on tabs, 32x11.5 on 15x8s, CB/PA, black out heads/corners, lil sound system, cranked t-bars, flow 40 dumped, line-x, shell, bed rug, 06+ tails, metal tail gate handle since plastic one shattered, OHC, Mustang Dome.