...I used the black and as mentioned elsewhere it was a booger.
FIRST I cut me a piece and worked it around the grooove in my 52 chev. panel and thought would go easy. NOT so.
I tried it from either end, also tried it by sliding it down on the back side and hoping to pull it around the rest. NO go.
I then opened up the channel a little but it was really to much and didn't hold the windlace tight enough so I ended up squeezing it back together.
The welding "spots" around in the channel also made it tough.
So, in the end, and after 3 hours of frustration I pushed it in using a nice flat/wide screw driver and it went in nicely.
I have a piece of the original and even though I know it has shrunk some the part that slides in the groove it not as "thick" as the black repop stuff and I believe that is where the problem is. Either way I don't want to do another one any time soon.
Thats my story and I'm sticking to it!!