Along time ago when butyl was used alot, rubber 'setting blocks' came in a box, which is what you can use instead of the factory setting blocks. But what ever you do, use urethane with urethane primer to install both the windshield and back lite and if you can lay a bead of urethane down good enough, you wont even need any butyl tape. If you cant find any of the rubber setting blocks, give me a snail mail addy and I will send you 2 of them.