popping noise from front spring

Cannot look at picture and rate condition of bushings. Some times a bar can be used between the spring eye and hanger or use a small hydraulic jack between the spring and frame. Jack it intell a fair amount of pressure is reached and watch the movement at pins on release. Also look at the space between hanger and spring on each side. If one side has twice as much gap no need to check farther. The shinny place on the pin is from it sliding back and forth. When it slames to the end of it's travel it will make a loud bang. All brand new stuff with side clearance will do the same thing and can be corrected with washers between hanger and spring on both sides.

 

Looks like a newer Peterbilt front end. Yes the whole upper mount comes with the pin and everything together, while it's apart have the spring bushing replaced. There are supposed to be rubber oring looking biscuits where you took the picture of that gap, the new pins and bushing kits will come with them.

 

Change the bushings while its down

 

Just changed the back hanger and pin. Couple hr. job. Its was on a Pete 359 and mine had washers on each side of pin so there's no side play. Not like your pic.