My 95 ram 1500 4wd makes a loud whining noise when I press on the gas. My four wheel drive won't engage either. What could this be?

 

Does it whine in neutral? If it does, open the hood, reach in and crack the throttle a bit, and see what you hear. Probably a bearing on a pulley, or water pump.... (or, low on power steering fluid.)

Check for vacuum at the CAD on the passenger side of the front axle. Should be vacuum at the outboard port in 2wd, inboard port in 4wd.

 

It only whines when I'm driving down the road. It sounds like it would if I was driving in reverse. Torque converter maybe? If that was the case, wouldn't I notice some power issues?

 

The whine seems to be in sync with the accelerator pedal. If I let off of it and cruise I can still here it but it's very faint.

 

I know that this is going to sound ridiculous to you guys but, what is the cad? I'm not a complete moron when it comes to vehicles but I don't have a lot of experience with trucks.

 

It sounds like you might have a bad pinion bearing in the rear axle, maybe. I had this same problem with the same symptoms you describe on another vehicle I used to own.