Good golly, Miss Molly. That ALL CAPS SHOUTING is a thing that must go.
'89AL' refers to the movement itself, not the model number.
A quick google search for +'Seth Thomas' +'mantle clock' brings up ten pages of results. One of these has to be yours:
http://snurl.com/ke9
There's one on this page with your same movement:
www.hortonsantiqueclocks.com/catalog/pg25.html
The most important thing about your clock is 'been in the family along [sic] time'. Doesn't anyone in your family know whose it was, and how old it is?
