Maybe I'm over thinking this. 9.1.4.L.1 says:

The battery may be replaced with any equivalent battery of the
same type. Battery may be relocated, but must be secured by a
tie-down bracket and positive terminal must be covered to prevent
accidental sparking.

What is an "equivalent battery of the same type"? Does this just mean 12v, or does this mean the same battery group number? In other words, am I stuck with the stock size battery?