I have a 1996 5.0, 2 wd, suburban. When I put it in gear Reverse or Drive it makes a whinning noise, more like a spinning noise it never made before and it feels like it is having problems in shifting. But when in Neutral the noise stops. I am sure it is associated with the transmission all the fluids are up to the proper level. Any advice?

Changing the automatic transmission fluid to a high-mileage type may help; but, no guaranty.

Changing the transmission fluid will not hurt, but I am guessing that it has been a very long time since you last changed it. That would hint that the damage has been done and changing it will not fix it, nor will it cause any damage.

Transman will likely show up and give you some specific advice. I would follow it. It is the man when it comes to transmissions.

Can you describe what you mean by “problems in shifting”?? What is it doing??
Is it pulling in reverse?? Does it upshift all the way through overdrive??