Help Identify this tank!

Hey guys I've slowly been working on my bike and figured its time to sell the tank that came with it. I originally believed it was from an XJ1100 due to the size but now I'm getting confused and starting to believe its from an XS1100, maybe a 1979-80 tank. Any help identifying this tank would be very helpful and if you're interested in purchasing it, please PM me.
Thank you guys and sorry if I didn't post this in the right section, I wasn't too sure where exactly to post.

 

you can see a 1100 tank in this thread next to a 750 maxim tank
https://www.xjbikes.com/forums/threads/fuel-tank-interchange-information.109290/

 

79-81 XS 1100 special?

 

looks close
the 1100 lh or 1100sh
https://www.partzilla.com/catalog/yamaha/motorcycle/1981/xs1100lh/fuel-tank

 

XS1100 tank, they have that funky latching mechanism at the front of the opening. XJ1100 tanks use a traditional cap that latches to the inside lip of the opening.

 

The XS has two fuel out ports on the petcock though, well at least my 79 does. This looks to have only a vacuum and one output fuel port.? Left petcock looks to have the vacuum nipple broken off? Just guessing...

 

1979 Special models used a "traditional" vac-operated petcock (2 of them), instead of that funky 1980-81 type with the remote vacuum unit....the 1980-81 used a manual fuel valve (2) (with no vac assembly on the "petcock", since the vac functions were handled by the remote unit) and those 1980-81 fuel valves are the one with 2 fuel ports per "petcock". The 1979 Special "petcocks" look like the ones pictured.

Now, that doesn't mean that it's a 1979 XS1100 Special tank, but it could be...……...but, for sure, it's not an XJ1100 tank because of that funny latch in front of the fuel opening.

P.S. All 1978-79 XS1100 models (Standards and 1979 Specials) used traditional vac-operated petcocks, and would look like the ones pictured. Only the '79 Specials used the teardrop-styled tanks; the Standards used the squared-off "breadbox" shaped tank. If your '79 has the no-vacuum, dual-fuel-ports on the petcocks, then it's either not a 1978-79 tank, or, someone has swapped the '80-81 fuel cock system onto a '79 tank, etc...……..or it's not really a '79 model bike (without VIN corroboration, those early XS11 models are pretty hard to tell apart!).

 

Thanks everyone for the help! I'm going to go with Chacal's suggestion of a 79 XS1100 tank. Might be a special because it does have the vacuum operated petcocks.
I'm going to try to get the guys from the XS forum to help me exactly identify this tank.
Thank you guys again!