The changes from RFC 1253 are the following:
"The value FFFF is distinguished to mean 'no route via this TOS'."
"The IP address of this neighbor."
to
"The IP address this neighbor is using in its IP Source Address. Note that, on addressless links, this will not be 0.0.0.0, but the address of another of the neighbor's interfaces."
This is by way of clarification and does not change the specification.