I was just in the same position yesterday. I bought some AGS Sil-Glyde Amazon product hoping to recondition the glass seal. When I was washing the old seal (from at least 1975) I notice it really wasn't pliable enough for me to be sure I could get the glass in and for it to seal properly on the frame. After busting all the rust off the frame and painting, I decided that I will spend the money and make sure it's right. CCOT sells an aftermarket seal for $48. I went ahead and ordered it to be safe. https://www.coolcruisers.com/wiglloseru66.htmlI just got the windshield glass out of my '76 FJ40 yesterday and the weatherstripping is in good condition, although 45 years old. I removed the windshield because I'm painting the rig and plan to reuse the glass and weatherstripping. The rubber is untorn, uncracked, flexible but dirty. I've had good luck in the past cleaning up rubber things like weatherstripping and hoses using Westley's Whitewall Cleaner and will probably use that on the windshield weatherstripping but my question is what to use after cleaning to keep it nice and flexible, and also black of course? I've used Armorall, 303, and various Meguiar's products for all kinds of rubber trim but looking for more of a "conditioner" than surface coating to renew it for the next 45 years. Any suggestions?
Reading this thread I see new Toyota windshield weatherstripping pretty cheap, less than $75, so maybe I should just go new. But I hate not reusing something that I can fix-restore-recondition!