I have found the Optima batteries are a bit shorter than the wet cell batteries for my truck.
I countered this with a length of 1"x3/16" flat stock and 1" square tubing. I tack welded the flat stock to the tubing and drilled holes in each end of the stock. This utilizes the stock hardware and locations for mounting and the battery is more secure than using a bungee cord.
The new hold down bracket is stronger than the stock unit and doesn't look too bad either <img src="/forums/images/graemlins/notooth.gif" alt="" />

1985 SR5 4Runner
eLocked with Carter Lock
4.7:1 single case
Davez Offroad twin stick