It's been a million years since mine was done, but here is one source.
http://www.glapinc.com/Cessna/337/337a.htm
Here is a refence for what they originally used on C170s.
As I recall, the original on my '69 'thrasher was also super thin.
"The original windshield was 1/8" thick thereby needing the aluminum center strip(IPC 051000-16) down the center (giving rise to the erroneous "two-piece" name). Any thickness windshield you buy can be tinted. If you select the 1/8"thickness you must use the support strip. If you order the 3/16" thickness you may opt to leave off the strip*. You may not be able to install the new windshield an easily without drilling off …"
http://www.cessna170.org/forums/viewtopic.php?t=554
And another interesting article:
https://www.avweb.com/news/features/...-225181-1.html