Unfortunately the Tankograd reference still does not exactly answer the question regarding the tarp over the ammo locker and crane.
The best answer would probably be found in the original TM manual and the best place to get that information (short of tracking down the TM itself) would be to order this disc from "Easy 1 Productions" which contains the entire manual, page by page, AND MORE.**
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Check them out on Facebook at:
https://touch.facebook.com/Easy1CD/** This is an unsolicited product recommendation. I am not affiliated with Easy 1 Productions in any way.