95 s-10 blazer engine whine

I recently had the catalytic converter replaced on my 95 s-10 blazer. since then, I have noticed a whining noise that comes from the engine compartment whenever the car is put into gear. In park the whine is either non-existent or so low that I don't notice it. I checked the transmission fluid and it is fine.

Can anyone give me any ideas on what may be causing this noise?

Thanks

Was the engine running and warm in park when you checked the fluid?

It was not running. I forgot to mention that the noise will increase and decrease with acceleration and deceleration. I am pretty sure that the noise is coming from the transmission which was a remanufatured unit installed about 40,000 miles ago. Funny thing is I had it in the shop to get a new muffler and catalytic converter installed and I started noticing the noise after that work was completed. We don't drive the truck alot, maybe once or twice a week if that.

You have to check your transmission fluid in park running with it completely warmed up.

Thanks for the advice but I took it to a trany repair shop and they told me the torque converter was shot. I had a rebuilt trany installed over the weekend and now it sounds much better.