68 windshield install question.

Ok I have been reading until my eyes are bleeding. I will definately be using butyl. I am concerned about the thickness of the butyl and the trim fitting correctly. Most people say to use 3/8 on the windshield and 5/16 on the rear glass. Then I see that they say that you should use 5/16 on the windshield for original glass and 3/8 on new glass because they are not as thick as the original glass. I dont like to guess on anything. I saw in one post that the rear glass, original or new is the same thickness. The post also states that the rear glass should be .237 thick. So for the rear glass I can say that 5/16 butyl with a .237 thick glass is correct. Now I would like that information for the front glass. Does anyone have or know the thickness of the original glass and also for the new repop glass? Any real world experience? I would like to end up being able to make this statement. "3/8 butyl is to be used with a windshield that is ??? thick and 5/16 is to be used with ??? thick glass.
Thx Boys
'Bill