Its a matter of "look" that you like. For function they don't add anything, but for "clean look" they are the way to go. You have to buy a "one piece window kit" to convert. Many suppliers carry them. Just make sure and use the kits with the "snap in" seals (scrapers). The glue in or screw in kind are a PITA!
As for install they are fairly easy to do. You must cut out the small strip of metal thats part of the inner and outer door connection, and also serves as a mounting point for vent window assy.(if I remember correctly). You must also remove the door "check rods" and install "one piece window check straps", if you don't, you will break
your new glass when you shut the door with window down. Also if you have a pre'65 bug you must switch window regulators to '65-'68. Some kits come with "destructions" some don't. Hope this helps out.
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1970 T1 W/MassIVe 2913cc RAT/?EFI? w/direct fire (very soon) and 915 trans
1962 SC 1776cc SP 944NA brakes, 993 wheels
VKG