Can you identify this tank?
 

I have this in a pile-o-parts that came with my RD350. I would like to ebay it, but it would be easier if I knew, for sure, what it came from. There is not a real serial # or anything on the tank.
Also, does anyone have good non-destructive ways to bet the cap off without a key. I want to check for rust. Otherwise, I will go through the petcock.

http://img41.imageshack.us/img41/911...kitankside.jpg

http://img571.imageshack.us/img571/9...akitanktop.jpg
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http://img853.imageshack.us/img853/7...tanktunnel.jpg
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http://img27.imageshack.us/img27/526...akitanktab.jpg
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http://img132.imageshack.us/img132/1...ankpetcock.jpg
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Any help would be appreciated.

Early 80's KZ 400??

I think the KZ400's tank was more rounded without the ridges on top.

I was thinking early eighties KZ550 or 750, but its hard to tell.

You might measure its capacity. That might help narrow it down.

KZ 650 SR or CSR as mentioned above.
http://www.thorn.org/images/concours/kz650_1.jpg

You could drill the cylinder of the lock. Use a small drill bit e.g 1/8 or smaller and gradually work your way up until a screwdriver will turn it.

I dont think you could open it through the petcock without accidently denting the tank or theres risk of ruining the lock by belting it open. Good luck