I think only the very early B-models didn’t have the bulletproof glass plate fitted. Later ones, like the P-40Bs based at Pearl Harbor seemed to have it fitted, as well as the AVG P-40s.
P-40Bs with bulletproof glass (at least I think they are Bs, they don’t have the drop tank attachments fitted)
P-40B at Pearl Harbor
The ex TFC P-40B, a Pearl Harbor Survivor
AVG Hawk-81s
I would love to see it fitted or made optional on the Big Radial one. To me it’s quite a prominent feature on early P-40 models.