Hallo,
Free Books here. Most of them work but some of them lead to a login request which also leads to a free book if you can be bothered doing all that they want.
I have used this one a lot and it is constantly growing.
As a guest your download limit is 50 books per day! Should keep you going.
http://betah.co.il/booksCatalog.aspx
Just click on armoured vehicles and start searching for what you want.
Cheers
Alan.