Any adjustment to level mirrors?

'12 388..This may seem like an odd/dumb question, but is there an adjustment that can be made to level out the mirrors? I didn't really see where it looked like anything could be done but maybe someone here will know differently.
Specifically, my passenger mirror is off by about 1/4"-5/16" leaning down towards the outside. Probably wouldn't be a big deal, but pulling a dump trailer it's making the trailer look off when raising the box. Everything else appears to be fine and straight so not sure what happened to get like this...
Thanks.

 

There's no bracket to adjust like you are talking about.These mirrors are cab mounted not door mounted which kinda sounds like you are maybe thinking off? But I'll give it another look over tmw when I wash it up. Thanks!