I've been posting on this since 2004 at least 20 times check the searches.
THERE ARE NO CONNECTIONS TO THE DOORS OR FRONT DASH SPEAKERS IN VEHICLES WITH INFINITY SYSTEMS. Those connections are located in the Amp output plug only !
I know you have done a lot of work with the factory audio systems in these cars, however my personal experience with both my car and others doesn't agree with the door speaker statement. My 95, and other 2nd gen cars I have worked on, absolutely had connections in the factory radio harness for the front door speakers. The tweeters were the only speakers whose wires were only available at the factory amp output harness.
To the OP, you should try the following:
1) Disconnect the high level speaker output wires from the radio to the 70-7004 harness
2) Connect the blue wire on the factory amp adapter plug to the blue/white wire in your radio's harness (Be sure to use the blue/white from the radio and not the solid blue wire)
3) Plug the RCA's from the factory amp adapter plug into the corresponding RCA pre-outs on the back of your radio
If the factory amp is functional you should have sound from all 6 speakers.