Ok everything disconnected and amps powered up and one amp shows 43V DC at the speaker outputs. So do i need a new amp?
Yes, new amp, or have that one repaired. Bad output transistor(s) often cause it, but could be a driver issue, possibly other things, like vibration damage. That amp is bad though and will kill voice coils so don't hook any speakers up to it until it's fixed.
Test the other amp and make sure you can set the AC voltage with a test tone before trying it on subs in case that one has problems too.
If no warranty and you opt for a new amp, list that blown one on
ebay for parts / repair, someone will probably buy it to repair and you can recoup a small amount. Not much, but perhaps better than nothing.
If you were to attempt repairing it (not recommended unless you really want to for fun), sign up over at diyaudio and maybe someone in the car audio section will try to walk you through tests / repair, but might end up wasting more money trying to do it yourself. If warranty, just try to swap it out.
www.diyaudio.com
Also don't be surprised if that pair of subs that seen the DC voltage from that amp don't last as long as the other pair, that created a lot of heat in those coils.