I have been noticing a whining lately and I'm confident it's coming from the transmission. It's a standard 5 speed for a 92 5.0l. I hear it especially when decelerating, and if I'm at a stop I can hear it as the stick slides into a gear slot. I very recently did a lot of dynamat work on the rear half of the car, so maybe I'm just hearing more of the cars normal sounds up front. What do you guys think?

 

Have you checked the fluid?

 

Back in 87, my wife's 85 T/A with a T-5, the whining started like you describe, we had the Countershaft replaced. Whine gone.
BTW, in 5th, it was quiet

 

Honestly I haven't done any service on this transmission in quite some time. I will definitely check the fluid level before doing anything else. If that doesn't work out, I'll dig a bit more into the countershaft.

Thanks guys