G'day Oldmate
A warm welcome to these forums from me.

This model 45 is my favourite ...
mainly because a 450407 was my first new reel mower.

For just a couple of model years, SB painted the chaincase
and handle name plate in a crazed black finish.

This one is c1975, because it does not have the pentagon chaincase logo,
introduced c1976, when SB moved to Briggs engines - as seen here:

https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/85032/brochure-c1976.html

Many thanks for the offer to contribute - a form of 'giving back'.
It is amazing what members learn from other members!

Nice images for the record too.

Jack