My question is in regards to getting my front bumper to sit leveled on the pickup truck. I'm figuring it is a generic question to all vehicles.

When we purchased the vehicle used the front bumper was not sitting right on either side of the car (just below the headlights)



With the bumper still attached and after looking around i wrongly concluded the bumper was bent at the center possibly causing the drooping on the sides of the bumper:

(the bumper from behind, at center where license plate sits)



My conclusions were wrong. I finally removed the OLD BUMPER and installed a NEW BUMPER figuring since the new one is straight all around then it should sit / bolt against the frame of the car perfectly. NOPE it too still droops at the sides. Clearly the issue is NOT with the bumper. Now I'm wondering 2 possibilities:

1. Is the car frame which the bumper is bolted to (i use 4 nuts to attach the 4 bolts from the bumper into the frame of the car) properly shaped and aligned to allow the bumper to rest properly against it to create a leveled appearance? What are your thoughts on the shape of the car frame which the back of the bumper attaches to?

(the car frame which the bumper attaches to -- 2 metal posts with holes to slide the 2 bolts coming in from the bumper)
** last 2 photos in this set are the car frames from behind - below with the bumper attached **



** I notice a small metal piece sticking out the front of the car frame bar at the center. Does it serve some purpose?



OR

2. Is there a special sequence for tightening the 4 nuts to get the bumper to sit leveled? For example, after shoving the bumper in start screwing in nut on the driverside frame (left nut) THEN passenger frame (right nut) THEN driverside right nut THEN passenger right nut. The sequence will draw the bumper closer without it dipping at the sides?


Thanks for any help.