Hi. I've noticed a resonnating drone (deep base-like) in the truck cabin when I engage the drive train and when the truck settles into gear between 40-50 mph.

I was cheap when I needed an inspection an had an after-market muffler put in. I've been told that this muffler is likely the cause and should get a OEM.

What do you think?

 

The muffler will cause a drone depending on which one.

If you got a loud exhaust, you should hear it MOST of the time.
I put a magnaflow in mine and it sounds great around town and then once i get to about 50mph+ i cannot hear it over the, wind and tire noise. My truck is noisy though, maybe different with yours.

DId it do that before or after the new muffler.

 

It did it after. Also once I get over 50 I can't hear it either. I notice it most when I shift out of park into drive and then between 40-50. I personally don't think it is a very loud muffler at slower speeds like a higher-end magnaflow. I'm sure this is generic Nappa muffler. I just hope it's not robbing me of any horespower (because I feel like my truck is lacking some lately).

 

Sounds like the muffler is the problem. I'd try a quality replacement or go OEM.