Help identifying holes in rear frame

[focusedontheprize]

Currently boxing my frame and I want to make sure keep the holes for the rear bumper brackets. My truck did not come with a stock rear bumper. I believe I know what the holes are for the yellow boxes, however what about the red?



Yellow = bumper bracket holes
Red = ??

[dwcsr]

Yes yellow is bumper. The others may have been for other add on for a different model. There were also may holes in the frame they were "index" hole the sole purpose was to index the frame in a jig as it passed through the assembly line. If you have an assembly manual it will show whats used and what is "index".

As far as boxing, I wouldn't go all the way to the ends. Air flow through the channels helps reduce the possibility of rust build up from trapped dirt and water. It allows it to dry out as you drive should water get in. I also leave one or two holes in the lower rail for drainage

[focusedontheprize]

Thanks Dave

[greg_h]

I seem to recall some "indexing pins" on the front bumper brackets.