96 Explorer

Hi I have a 96 Explorer 130k mi 4.0 and when I put it in drive to accelerate it whines kinda and wont change properly the rpm run at about 3k at 70mph Im leaning towards the modulator but I can't locate it. I f you may have any visual help to locate it that would be great plus and alternative routes I may take in solving this problem or other things I should check please and thank you the sooner the better.