I found a pill that is a large elongated pink pill with 3667 on one side & an S on the other.
Could the imprint possibly read 86 67?
Yes it is possible.
S / 86 67 is SKELAXIN 800 MG
Imprint Code 86 67 / S
Description pink, oval, scored tablet
You will find an image at https://www.drugs.com/skelaxin.html
Info at http://skelaxin.drugs.com