I had my windshield and backlite both "professionally" reinstalled with new rubber gaskets. The glass guy told me he had done hundreds of installs on early MOPARS, and that if they were to be installed with fresh new gaskets, that they could go in "dry", without butyl or any kind of glazing or sealer. However, AFTER he completed the installation, he informed me that the gaskets that I purchased must have been some "cheap china junk", and that he wouldn't guarantee the job against leaks. In fact, he virtually guaranteed me that they would leak, and leak they did! When I asked him why he didn't use any sealer if the gaskets fit so poorly, he said he had 4 more quick urethane jobs that day, and didn't have any more time to spend on my car., He was also doing my car on the "side" through a mutual friend, you know, cash job, no receipt, no tax.
I had to reseal the glass, myself, between the seal and the channel, and then between the seal and the glass itself with ALOT of 3M Bedding and Glazing compound. Front and rear.
If you glass doesn't leak , and it isn't fogged up around the edges, I would leave it alone. Unless of course you have a good glass guy that you trust, which I I replaced windshields and rear Glass on my cars. Not hard at all. You have to use Butyl Round Tape, no matter what,around the gasket you are using.First before you put the gasket around the window that Glass sealer in the tube you buy at paint stores must be used! It must be used between seal and glass then Ronson Lighter Fluid, used to clean it while setting up! You need proper tools and they sell them at Classic Industries, and Year one probably at Harbor. but I would stick with Classic! 1- you have to have the Rope with the Handle attached 2- you have to have the Rope style Long *** Roll of the Buytyl round Style Buytle tape. Kinda thick but that is fine. Next you need that red handled tool with the Ball on the end of the metal extended part, a must so when you want too pull the lip of the Rubber after you pull the rope. If I recall, I put the Black Only Round Butyl and roll it out into the groove on the inside of the gasket. Then press the Rope into the round BUTYL. Yes, they are kinda what I’m saying Combinedthe rope on top of the Butyl. press tbe rope into the Butyl. Next you need the suction Cups four of them. Also a person with their head screwed on that can follow Instructions. So once the gasket is on the window, with the glue that comes out of the tube and that seal is cured pretty good install the round Butyl into, the out side part of the seal, then push the rope into the butyl all the way around the window and seal! Lay a nice Moving Mat on top of a Blanket on the Cowl! You might have to pull windshield wipers? Just do it makes life easier and buy the tool that removes them! When ready, oh? and the antenna could get in the way? Anyway tell your buddy to attach suction Cup and togethor get that window up onto the Cowl or window ledge remember the rope has a Handle this will be on the inside of car! So think about what direction you want to pull your seal? I leave mine on the driver side! I also remove the steering wheel so that is not in the way! When pulling on the rope. You should have a set of suction Cups on the outside.and inside! Inside is questionable.but you can move one around if needed. Anyway put that gasket and window on the bottom ledge being sure the gasket is on the Pinch Weld all along the bottom! I push on the bottom of the window pressing the seal so it seals between the pinch weld pushing on the window then if the bottom is on the left side pinch weld I start pulling the rope handle gently and slow while the the window falls into place! This is not a race! The window might bend some while you work them into the Gasket and Pinch weld. As you pull that Rope the rubber slips over the inside pinch weld. You want to keep your red Handled tool with the small ball at the end and slip it under any part of the seal that might not have slipped over pinch weld. It works as you gently pull the rope as the seal slips over the pinch weld slowly!!! This works and I will never use an installer not willing to use Butyle Rope and these tools even after installed you can take Butyle and shove extra between the seal! Wish I was 30!years younger I did these frequently and they sealed every time! Good luck! If you need any help let me know I can give you tips as to install your Windows also Tape all around the window with a recommended tape that won’t harm your paint when removing but applying it will protect the paint too! Also I replaced all my windows had Numbers etched in with the Chrysler Logos. I measured the new windows they were exact thickness so where people get their measurements from I don’t know! Mine were correct thickness. Maybe that’s why they sealed?