Ok Geniuses, FW4042 and FW 3138 and 39. What is the actual difference between the two windshields. No official interchange exists between models. No one stocks in my part of the world Mygant, Pilk or PGW or ever has. I've installed the Plug in model and it looks the same as a FW3138 but never have done a side by side comparison.
Here is the story: Repeat customer calls me looking for a windshield on a 15 Prius plug-in. A service writer gave her a price of xxx for an aftermarket glass and she wanted me to see if I could match it. As I could not find the FW4042, I won't/can't quote it. She called the glass company the service writer was using and was told that yes, they were quoting the regular Prius glass but they would indeed put it in her car, encouraged her to do it (Hack Attack) but would not be responsible for any differences. I told the customer she was crazy to trust anyone who said that and that unless she knew the exact differences, do not do it. As the cost for an OEM windshield and a budget priced 3138 is over $1K, she wants the cheaper glass. I'm more worried for her in regard to warranty and liability issues.
I've seen distributors not carry some early 2000 model Acura TL windshields as there was a minute difference in rear view mirror height between the 2 door CL and the 4 door TL. However it was public knowledge of that discrepancy and they were commonly interchanged. Not here?
What's the difference?

FW3138GTYN OEM:56101-4E933 w/Third Visor
FW3139GTNN OEM:56101-4E929 w/Third Visor / Electrochromic Mirror
FW4024GTNN OEM:56101-4E928 w/Third Visor / Plug In

Read this:
http://www.toyotanation.com/forum/62-prius-forum/448337-2011-2013-prius-prius-plug-windshield-issue.html

There’s a different third visor, mirror patch and location as opposed to the five other non-plug-in vehicles.