Best I remember they are dual VC, something like a 1.2Ohm load or similar. Shelby sells a Kicker drop in replacement as well. The best solution to the Shaker system is, unfortunately, to replace the whole thing. There are some pretty good write-ups floating around on different system solutions.
I just put it all together, after finding that FUBAR wiring and the two Chinese amps. I'll replace it all soon, but my money is going to long tubes first!
2007 Mustang GT 302 stroker 6060 swap, 3.73 gears, Hidden Hitch Receiver, Barton Short Throw, JBA LTs, Borla Touring Axle Back, Lito tuned SCT X4. BMR SP009, Bilsteins, J&M CC plates, J&M LCAs. 4 Piston Brembos
DOB GT450 with VMP Gen II 2.3 TVS | 13/14 GT500 HE & IWP | GT500 hat & DW340s | FRPP 52lb | CMS Stage 2 Blower Cams | Comp 113 Springs & Retainers | 8 rib conversion | Track Spec GT500 Vents | PTFE Heat Barriers