I have a blue '87 tank without a cap, if you can use it.
87 tank - 4.jpg
87 tank - 3.jpg
87 tank - 1.jpg
87 tank - 2.jpg
There are a few rust spots on the outside, but the inside looks great! Not bad for a 30 year old tank.
I kept it in case I didn't like my XT350 tank swap... but I'll be keeping the 350 tank.
I wouldn't mind trading for your Clark tank, if that works for you.