Originally Posted by
Yamato72
Personally I consider anything with a threaded stem to be older as that's a good indicator that it could be a challenge putting modern components on the bike.
It also depends on what you are looking for. We moved our 91 Cannondale down to our beach house in South Carolina and it was a blast riding the grand strand. It is old tech with brifters but is bomb proof and rides like a rail along ocean blvd at 20mph. For the right price an older tandem is a good starting point. We are up to 3 tandems now and each has a different purpose all at less than the cost of a recent tandem.