We (my dad and I) put the headliner in my '48 half ton today. I've been dreading this job, but it went well. On the '48 the center bow is attached with 11 screws, and the front piece goes under it, so you have to start with the front piece. I've heard a lot of people say the headliner has to fit under the windshield rubber, but that's not the case with my truck. The only pieces that had to go under the rubber were the two short pieces that fill in the windshield posts.
The first thing we did was remove all the screws from the door windlace down to dash level and the equivalent height behind the door. It really hurt to do this because of how difficult it was to get them in in the forst place. This has to be done because the headliner goes under the windlace, and removing that many screws allows the windlace and trim to be pulled out enough to work on everything.
We put washers on four of the screws that hold on the windshield trim and put them part way in across the top of the windshield. These were just to hold the front of the cardboard while we adjusted things. Oh, and we also sprayed water on the backside to make it more pliable.
We put up the cardboard, then held the back in place with four screws and washers where the center bow goes. Then, after making sure everything lined up, removed the holding screws from the driver's side of the windshield header and installed the trim on that side. We repeated it for the other side.
Of course, not everything lined up, so we had to enlarge a few slots so we could get all the screws in. With the windshield molding on, we remover the rear screws and put up the center bow, then made sure everything was tight. Now, I don't know if others faced this problem, but there's no way we could get the end screws on the center bow. They weren't even close to lining up, so we left them off.
On to the rear headliner piece. Here's where the fun was. This piece was too large. On the '48, the leading edge of the headliner piece slides into a slot on the center bow. This wasnt easy to accomplish! Remember the missing screws on the center bow? Well, having them missing alllowed the bow ends to spring toward the rear somewhat, which made getting things lined up rather difficult.
Like others have noted, the cardboard wasn't cut right. We centered the notches with the rear trim screw holes, and made new holes. We had to keep pressure on the rear of the cardboard to keep it forward enough, then I used a Dremel tool with a cutting bit and elongated two of the notches, one at roughly the center of each side of the cab, so we could put up the trim.
Our intention was to put in a few screws, mark a line, take it down and cut the cardboard. What we wound up doing was a lot easier. The rear of the trim fits inside a slight channel at it's rearward edge, so we could line up the trim piece with the channel, then use an awl to punch through the cardboard and into the hole in the roof wher the screws go. It worked perfectly. We worked across and got all the screws in the rear trim.
This left about a quarter inch of cardboard sicking out behind the trim. I trimmed it off with a utility knife, changing blades frequently to make it easier. It came out very well.
We then went through the frustration of getting the windlace and trim back up.
The only things left to do is install the "T" trim pieces over the junction of the center bow and the windlace trim, which should allow us to push the ends of the center bow forward and into place, plus figuring out how to make holes and install the sun visors.
