You asked my type of question, I work for Kicker Car Audio....
The Monsoon came out in the late 96's to early '97. Yours has 6 3/4's upfront in the door, and 4" in the rear side panels and 6 3/4's in the rear seat side panel.
We make a speaker to replace the 6" sub in the rear that alot of guys are going to. It's called the Freeair F65C4. Should work nicely.
383 Speed-O-Motive stroker kit with Holley 750DP, RPM intake,Proform HEI dist.MSD6a box,World Products Sportsman II heads, ported and polished with 2.02/1.60 valves,64cc,TRW forged pistons with 10.7:1 compression, Comp Xtreme 284 cam,Crane pushrods, Comp Cam 1.6 full roller rockers,ATI damper, 40 series Flowmasters, 4.11 gears with TH350 and Hughes 3000 stall.Powertrax NoSlip Locker