The following images show the battery hold down J-bolts with a measuring tape to see the lengths.
These first two images are of a pair that I ordered and bought from a Chrysler dealer in the 1980s. The shorter one arrived with a different finish than the expected black and a slightly different shaped hook.
These next two images are of a reproduction pair that I bought from Year One in 1995. The hook is different than stock, and they have no coating on the metal, so they rust easily: