Transmission fluid confusion
 

First, thanks for taking the time to read. I'm scratching my head about this one and need some help from someone with more knowledge on this.

What is the correct ATF for my 2009 F-150 with a 6-speed (6R80) transmission? I have a Haynes manual which recommends Mercon LV for the 6-speed, but when I removed the dipstick, it says "Mercon SP" printed on it. My initial searching online confirmed that they are NOT the same and should NOT be interchanged.

I purchased the truck from an aging family member with zero mention of installing a new transmission. And with the low mileage (92k when purchased), I'm hoping he did not "forget" to mention a new trans install.

Please, can someone help me understand why I'm seeing two different recommendations? Which should I respect, Haynes or the dipsitck? I'm very concerned that I'll cause damage if I choose wrong.

I've include a picture of the Haynes recommendation below.

Thanks in advance.
https://cimg0.ibsrv.net/gimg/www.for...5f2ccc79fb.jpg
Haynes Repair Manual, Ford Pick-up, 2004-2014; Page 1-1