62 impala noise problem

We have a 62 impala that we did some work to:

-changed head unit to aftermarket shaft radio to keep stock appearance

-took 4x10 in dash and put 2 4" in place

-replaced fact. 6.5" in rear seat

-installed mono amp and subs

-installed FM cd changer

The problem is an engine noise through the interior speakers. It doesn't sound like a typical alternator whine. Its more of a clicking sound that changes with the RPM's of the vehicle. I tried regrounding the deck, alternator and battery. the deck and the alternator both have less than 1ohm of resistance to the battery's ground terminal. The power wire is going to the ignition harnes along with the accy. The speakers are not grounding out either.

I think its the deck that is causing this problem, but I was curious if there is anything else I should try before officially blaming it on the deck.

only the subs are amped. the interiors are not and even with the rca's unplugged there is still noise.

thanks to all that have suggestions, but you all need to read closer. RCA'S HAVE NOTHING TO DO WITH IT. THE INTERIORS ARE NOT AMPED AND THERE WAS NOISE WITH THE RCA'S UNPLUGGED. Like I said in my last post we wired up a new radio and that took the noise away.

DUCT TAPE:  We tried to upgrade pretty much every wire in the car with no success, but thanks anyway

Bottom line, the customer is happy with his new deck no issues anymore.