If you are speaking about trimming a Wagon tailgate, This may help.
I have a 71 Nomad Wgn. ( no trim at all on T.Gate). I also have a 70 LS-5 M-22 El Camino. ( This was my guide for my wagon build)
I did my Nomad T, gate to match my 70 SS 454 El Camino. El Caminos have a long & a Short tailgate trim. I believe I bought two SHORT pieces for a 70 to trim my tailgate on my Wgn. My first SCREW/UP was using the old Org. 1970 El Camino trim to mock it all up. Mock up DONE all is perfect drill holes in T-Gate, Test mount Org. 1970 El Camino trim from my one owner. Wagon is painted, Go to mount REPRODUCTION -1970 El Camino tailgate trim. REPO stuff is a whole nother Friggen story.
When you mount the 1970 Camino trim on a wagon-68-72, OFFSET it to the right just a little ( no/one will notice it) WHY? When you open the gate like a door the 70 Camino trim will ALMOST hit on the left side. The thin or skinny factory trim has an embossed depressed area to clear the left side tailight area.
How much is my trim offset? From the edge of the trim to the edge of the door on the R. Side,, About 1/8" of an inch. Offset on the left side is about 1/4" of an inch. Or in nine years or 37.000 miles no one has ever noticed it ! For the factory weld on rivits AKA studs to hold the trim clips,,, I used the little Phillips head screw in studs.
My wagon is the VERY SELDOM SEEN COLOR IN 1970 ! ! OH GOD its RED !
If you have any questions just ask.
P.S. My wagon is a 1971, It was punched in the nose,,,, It now has my old 70 El Camino front clip. My 1970 SS 454 Sta. Wgn. is a FRUAD, And I have papers to Prove IT !