What is that noise?

I have an 06 Tacoma PreRunner Quad cab 2wd 4.0. When I am in gear and at idle I hear a low rumbling noise. Is that my torque converter? Today I was trying to find my Transmission dip stick? Is the tranny a sealed unit that has does not have a dip stick?

I had a small travel trailer for a short time, dry weight 2,600 lbs. Only took 3 trips and sold it because my Tacoma just did not seem to handle the weight, gear box hunted for best gear when climbing.

Too many questions in a single post?

 

It’s a sealed unit.
There is not a dipstick.
The best gear for towing is 4th (in my experience)

I don’t know what the noise is, it’s hard to tell.
It could be anything from an accessory driven by the belt to the transmission.

 

Thank you for your time and effort

 

I have to be honest, I didn’t put much effort into the response.
Diagnosing sounds on the internet is really hard.

But I will provide you this, so that you can check the level.
I’ll go ahead and tell you, it can be frustrating.
https://www.tacomaworld.com/threads/how-to-drain-refill-automatic-transmission.63851/

 

Thank you so very much!