2010 Tacoma makes strange noise.....

I have a 2010 Tacoma double-cab. Lately I have been hearing a strange noise when I first put it in drive and step on the accelerator. I don't hear it any other time. Not when it's idling, not when it's in reverse, or even when it is in drive with my foot on the brake. Only when I hit the accelerator to pull out and then I never hear again until I start it and take off next time. It's almost like squeaky mechanical sound like something is either opening or closing. I will add that I have taken the stereo out in preparation of adding a new one so there is a big hole in the dash which may be allowing me to hear something now that has always been there. In addition, as a result of the stereo removal, the airbag is showing up as being disabled for the passenger light and is lighting up accordingly on the dash. Any ideas as to what I am hearing? Thanks

 

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