JD, even though your truck is a big bolt, the headliner is the same all the way down to a 1/2 ton in '46. You might get a better response by asking the question in Interiors. I performed the installation in my truck, although it was back in 2003. I think I used water to dampen/soften the back of it but I remember it being a bear, especially by yourself! Lots of sweating and cussing. I think mine required some trimming too to get it right. Also FWIW, my headliner shrunk above the passenger side door over the years. It could have been because I trimmed it a little too much? or I perhaps it was because I didn't use any insulating product on the roof? or it because it has sat out in the sun at too many car and truck shows? Don't know but I wish you luck with your install.
