Pretty sure I have an extra 84 br tank. How can I tell what it is?

[tri again]

I'm fresh outta 84 br models but have a tank that is of the not rusted variety.

I'm so buried in tanks right now trying to get them all hung up and dry
for winter I just can't be sure, how to be sure which one is from the 84 br....

and then I'll post it in the classifieds.

Thanks

[atc007]

If she's a real beaut,I might take it.