Stance question
 

The truck cab and bed on my '69 K/10 are both not level. I'm fairly certain that the cab is a spring and shock issue. The bed however is level at the front and crooked at the back (vertically). What could this problem be? I've looked up under the bed and the spacers are turned different ways, but I'm just not sure if thats it. How can I check and find out? Thanks