"El Chachacha Del Arpa" is the B-side ("Lado B") of the "Felicidades" 7". Lado A is "La Cancion Del Muchachito," and it is a ballad. I could not find out when this was recorded, but a little googling led me to Senorita Salcedo's blog. I e-mailed her and asked if she remembered what year this was recorded. If she gets back to me, I'll let you know!
I feel especially lucky to own this because it happened to be signed by the Bold Loving Edith Salcedo herself, on the back cover of the 45 sleeve: "To HENRY with pleasure"! I took a picture of it with my phone but it didn't come out good. I need to get my scanner hooked up.
Download: El Chachacha Del Arpa