We used NP1. Got it in a bunch of colors at Lowe’s about $7 a tube. Used it on cab floor repair sealing top and bottom and bed seams before rhino lining. It’s been over a year and we are water tight everywhere and no cracking even in Texas heat.
Randy and Easton
Good stuff, except wrong application IMO. It should bond well and not crack, but it, like other NP1s and all the different Sika Flex products I’ve used are far more flexible than seam sealer (and consequently less durable in an application like inside the bed or the rear bumper seam, or even cab seams as just a push with your fingernail can/will deform it which will pop the paint off if it’s a painted surface). The stuff you used is specifically designed to be flexible like for expansion joints in concrete. It’s make to stretch ___% of its width and retain the bond to the substrate.
Just use seam sealer or something like 3M 5200 that gets much harder to the touch.
I’ve used AC Delco and 3M (or SEM) recently. Both are still good a couple years later now.