Hi Mark,
The 4 battery strap mounting locations are only threaded from about half way down and do use very long (1" +) screws (or threaded rod) to hold down the strap. If you are only putting a 3/8" or 1/2" screw down into the hole you will not find any thread at that depth. This was done so that you were not screwing a sufficient screw in miles and miles to make it a secure hold on the cells... (if that makes sense)
The "Real Men Wear Black" XF1226 Battery Stand Off kit is ideal for this very job....
