radio interchange question

I've used some of these Retro Sound and others in B and E bodies and I've found that they use a cheap internal amp that sounds like crap. Goes real loud but has a lot of distortion. Use a separate power amp and they work good as a head unit/preamp.
Also is funny how these companies don't know what all their product fits. 68-69 are different than 70 and if it fits 70 then it will fit 70-76 in an A body.