Possible Gary Larson? 1 1

[BlancoBros]

I acquired a piece of art, I'm unsure if this is sketch is by Gary Larson or drawn by someone. Any suggestions who to contact about verifying it?
It's pencil on paper, mounted on a blackboard. It's of the Far Side strip - "birds of prey know they're cool". I compared it to the b&w and color versions of the strip and it is slightly different. Noticeable on the walkmans and cords.

I don't have the piece in front of me, but it's a decent size, 10 inch x12 inch?, so it's not traced. The art is done pretty well and clean lines.
In the top right hand corner, "larson" is written in green pencil, but not stylized like his typical signature.
There is no other writing I saw on the front or back.

I purchased it in a poster lot at an estate sale earlier this year. They had other artwork at the estate; authentic vintage Japanese woodcuts, original paintings and lots of 1st edition books. So I didn't want to be quick and rule it out as not real. My heart tells me it's not an original by Gary Larson, but I would sleep better knowing for sure.

[Ecclectica]

For me, it's a traced fake, but for the others here, in order to express their opinions :