I am installing a new top, rear window, and pads on a 61 oldsmobile pretty much same as Impala. I had this car brought to me with the old top already removed so no type of pattern to help with. I read up with no old pattern I noticed the rear curtain had small holes which I noticed coincided with some of the bolt holes in trim stick. I stapled curtsain to the main rear trim stick put in car with a few bolts and stretched it to the rear bow which I set at recommended height with installation of new pads. I warmed up window with heat gun while I pulled it to rear bow have a little bit of dip right before rear trim stick and some wrinkles in window near corners. Does anyone have any tips or other sites that I haven't looked at for pointers. Am I right in thinking the holes line up with trim stick bolt holes? With no pattern from old top its making the job of knowing where everything needs to be more difficult. Next step when I actually put top onto trim stick do I just staple on trim stick were the holes match up with bolt holes and do I ever unlatch frame when installing top? "TIS THE SEASON TO BE MERRY?!!"
The best you can do on those cars are to staple the top and rear window to the tack strip using as few staples as possible and install to see how the top lays. Most usually your problems will lie in the corners being too tight making the window appear loose. It's trial and error, once you're comfortable with the fit remove it and staple it down good and re-install. Small puckers in the clear vinyl is easily removed with the heat gun and steam works great on the fabric, Those mark are for the bolt holes but I would consider them as just a starting point. There's just too many variances since all GM cars used that top and no two identical bodies measure the same.
Kyle