Hi Andrew,
Indeed, the IWM picture isn't much good, being too bright. But since the PhotoShop was invented such problems aren't problems anymore
The part of the photo of interest was enhanced a bit and I think it is more user-friendly yet:
Only this part enlarged:
How I see the place of the "INSPECTED" stencil, somewhat crude and approximate rendering but as close as I was able to do it:
Sorry for the pic, but there is no real Chevy 1533X2 in my garage, so I was forced to use my 1:76 model for this.
Regretfully I don't have the book "Kiwi Scorpions"
but I know it is good one. I hope some day it will be within my reach and I also hope I'll find some new photos in it. BTW, I suspect the pic of the trio I've posted above is from this book.
Cheers!