Thanks, but no, the Curly Fletcher song's not it. I checked. (It's Digitrad's only Vaquero reference to date.) This one, to repeat, had a stanza whose first two lines were A-B-A-B rhymes.

I am a vaquero, I wear a sombrero, My ............... my pony is Taw,...

By the way, it shares a tune with (may have swiped it in true Tin Pan Alley fashion from) an old 19th century humorous(?) song "Mother in Law" that goes:

I'd rather be sent off to jail or to Congress Than to live another month with my mother-in-law.

But I have been totally unable to find the Vaquero song, though it was a pop song on the radio in the 40s. It's a puzzle! Hope someone can help. —Bob