Adding tie down rails on top of bed sides

I had a 1999 Tacoma (350K miles and still going!) and I want to add aluminum rails with tie downs on TOP of the bed sides.I do not know what is under the plastic tops. (No shop manual yet) The issue is how to secure the rails. The 1999 was metal, so I tapped for 1/4"X20 flat heads. That was very successful. My only option may be self taps if there is no metal direstly below...doesn't thrill me to rely on that. Really don't like the included tie downs, good gesture but the engineering is abhorrent. The tie downs are awful. They also should be on the top of the bed sides to be more useful. Is there metal under there? What is the "secret" to lifting the plastic tops to take a look?

 

1st Welcome to TW from TN!

2nd get the bay area metal fab bed rail tie downs. Probably the best $71(with shipping) i have spent on the truck other then the weather techs.

I have some pic in my build in my sig.


also here is the link to the thread about them and how to order them.
http://www.tacomaworld.com/forum/ba.../234905-b-m-f-2nd-gen-bed-rail-tie-downs.html


edit: also i think it’s only sheet metal under the rail sides. but the channel rain thats on the inside and top of bed is pretty strong guys are putting 300+ pounds on them with bed racks and off roading gear.

but i agree the tie downs that move are not very strong, i did not like tying my dirt bike down with them. but i use them alot for light stuff, like to keep push mower or something from moving around. have tied some dry bags on top of coolers on a 650 mile road trip.