Usually the rear subs don't blow, the glued area that holds the cone to the speaker frame disintegrates. It's easier to fix the original dual 4 ohm voice coli speakers than to find ones that will work/fit and match impedance with your system. Tip to get the most out of the rear subs turn the bass to max
1. Here's a link for the repair kit: https://www.ebay.com/itm/13155190067...Bk9SR6bAnNL5YQ

2. how to video is for door speakers but same procedure for subs :