I have a 54 3100 and just installed a new headliner. On the 54 new flexible windshield and cab windlace rubber is extremly important in installing headliner. My windshield and cab windlace in brand new. Was able to install the headliner under both but it was a pain. The windlace rubber flexibilty is way more important and i would think it easier to install headline first. Not mentioned anywhere is the trick i found by accident. Use the metal center headliner bow as a guide to trim the cardboard edges to correct side to side length. Yes, you do need to trim it and its a hairy scary one try deal. Even more important is to wait till AFTER the headliner is completely installed to cut the holes for the Passenger side visor. Go slow. Use the supplied pattern to find the approximate hole locations with a small sharp awl and the visor bracket to get correct locations.. Another one shot deal with disaster a half mm away at all times. Lastly the rear headliner section usually needs to be trimmed to fit as well. Ignore what the experts say. Take the excess off the front edge and not the rear with the screw cutouts. IMHO the repop liners are all poorly made and shipped. My first one broke in half after a week of gentile flexing. Being tightly rolled saves shipping but renders the product very difficult to work with.

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