[LH Lead-Foot]

I have a 67 C10 long bed. If I understand the pieces you're describing, they are somewhat hidden with the tailgate closed and OEM type rear bumpers installed. Mine are painted black and never gave a second thought. The bed floor is wood and capped off at the rear with a rectangular stamped rail which I painted black also.

The truck was originally a "Blue" as best I can tell from under the dash. but not original elsewhere. So technically my answer won't help. The truck was sound, little rust except interior cab floor corners, but the previous owner had to be smoking something as the drilled 2" holes in the bed sides, all they way to the opposite side. It's like a pipe was used to hold down a camper shell.

Speaking of camper shell, the rear cab window was the small version. It was gone and replaced with a bolt in camper window. Yes, it looked hideous! My son got the truck, gave up after I had over 100 hours of welding, wiring and fixing electrical. So, it was given to me as he walked away. THE FIX!

I borrowed a cordless reciprocating saw with 3 batteries. Went to the bone yard a found one with large window and slider to boot. I mark it out oversized and cut the inside and outside skin to free it. Drilled out 50 spot welds, cleaned, epoxied and cold galvanized everything. After careful measurements, marking and final trimming, the out side skin went into an off-set flange created by my HF pneumatic flange/punch tool. I like the flange set up instead of butt welding and it works great. The head of the tool is adjustable to rotate 360 degrees to get the handle out of the way. Plus, the depth of flange & punch is adjustable for thicker or thinner to achieve a flush fit. After plug weld tacks while dead centered, I had every vise-grip pliers I owned on it. Factory uses a "U" shaped notch in panels for alignment and work great. The welding was completed with fiberglass short hair filler over the lead I melted in...outside only. Yes, I had to make some wooden paddles, had 30 sticks of official body lead (1 Lb. each) and 1 qt. paste flux can. The hardest part was sanding the inside upper con-caved cab corners. I spent 3 days sanding before my arms would not reach my mouth due to fatigue, then found black semi-rigid shipping foam chunks that comes from sheet metal purchases. Re-shaped one to resemble a ball with a handle, use PSA sandpaper and finish that job. That was hard. I will NOT do that again, but will watch & advise. Should have taken some photos, but retired and empty nester...wife is on phone and prefers the garage empty.

Sorry to get off subject, but spray some black guide coat or primer to see what you think.