Transformer Identification

[yano]

I came across a transformer, two pins on one side, 3 on the other. Only markings are on top, "51-97" and on a line below that, "989-7550" Any ideas? Its pretty small in size, about one cubic inch total.

[Paul Perry (Frostwave)]

The 51-97 probably means it was made in the second-last week of 1997.
And here is a remarkable (but probably meaningless) coincidence: there is a 220/110 to 24v transformer made by Hammond that has an Allied part code 868-7550. Spooky!