I have a Conservation Bond, issued by The Colorado Society for the Preservation of the Narrow Gauge, Inc., with two attached Passenger Coupons. The latter are interesting, as they state that, if the railroad is preserved, then I would be eligible for whatever consideration the operator of the railroad might offer. The bond is Number 0145; the envelope it came in is dated April 4, 1970.
(I could take a photo and post it here, if someone would give me the instructions on posting, which I've never done.)