1986 Passage is quite nice, excellent score. Be thankful it is not a 1994 (I just picked up a 1995). By the 1990s, the Passage was pretty basic, nothing special for sure.
The 1980s Passage was a really nice bike in comparison.
As far as serial numbers, even though Schwinns had some usable serial numbers, I don't bother. Instead, I just read the date code off the headbadge, takes two seconds to date a Schwinn. I wish other mfrs did this.
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Please don't confuse ebay "asking" prices with "selling" prices. Many sellers never get their ask price. some are far from it. Value is determined once an item actually SELLS. Its easy enough to check SOLD prices.