The version I have is the same as SHARON A. except that after the verse about "Back in the days of Forty Nine.." I have three additional verses. WATERLOO is mentioned in the second verse below.
When Zacharias Taylor gained the day
Heave away, Santy Anno!
He made poor Santy run away,
All on the plains of Mexico.
General Scott and Taylor, too
Heave away, Santy Anno!
Made poor Santy meet his waterloo,
All on the plains of mexico.
Santy Anno was a good old man,
Heave away, Santy Anno!
Till he got into war with your Uncle Sam,
All on the plains of mexico