93 explorer stock amp?

i have a 93 ford explorer. i have a pos pioneer H/U with 1 set of preouts. i have a cut off of some RCA cables.  I was wondering if i can use the stock jbl amp and 5TH speaker in the back. and if i can what color are the signal leads to the amp?1974 ford pinto 4 15" punch Z power punch bd 1001 pioneer DEH-6700

ok i found the amp remote wire. hooked it up .no sound from the 5th speaker in the rear. there is some wires bunched together. real thin wires like 8 of the . off the wall colors. i would assume those are the signal leads to the amp. just what ones are for that speaker? also i yhave a extra pioneer H/U. i was gonna just try using the chopped rcas and see if i can get signal to the stock amp. whith the extra H/U. if anyone thinks its a bad idea let me know.1974 ford pinto 4 15" punch Z power punch bd 1001 pioneer DEH-6700