so guys when i hit bumps the drivers side of the bed has a noticable wobble and this causes some extra vibration when hitting bumps to it there is a crack back there that i will be welding and i posted a question about why my bed may be sitting lower on one side and some people mentioned to check the shackles and the shackles look excellent so im not sure what it could be and however its not noticable to the average joe i know its there and it will bug me if i dont fix it soon.

 

I think you may have already answered your question...

But then again, "a crack" is very very vague.

Help us help you. Pics, videos, more info, etc. are very helpful. "A crack" doesn't give us much to go off of.

 

 

Why are you asking us what it could be? You already found it.

 

i wasnt sure because my dad thought it was the mounting bracket for the bed and im not sure how to check that im a first time truck owner

 

Crawl underneath- have your dad shake the bed- then watch carefully-it should be obvious where your problem is at that point. Then you can formulate a plan to repair or replace what is wrong.