I have an opportunity to buy a used Santana tandem for $500. Seller says it is 1978 but it is a 6 speed and I think Santana had 5 speeds in 1978 and 1979. So, maybe it is a 1980?? Anyway, it runs well. Has Phil Wood hubs. What do you think? A good buy? Or an upgrade nightmare. I am mostly interested in the wheels. It has a 140mm rear hub. Would a 145 hub fit with no real problems?
Thanks in advance

The rear triangle can be re-set to 145 mm spacing by any decent bike shop or frame shop. You might be able to get the rear wheel re-spaced to 145 also (or do it yourself) thread on an 8 speed freewheel and be more-or-less up to date! (I think Nashbar has some 8 speed freewheels on sale).

I have an opportunity to buy a used Santana tandem for $500. Seller says it is 1978 but it is a 6 speed and I think Santana had 5 speeds in 1978 and 1979. So, maybe it is a 1980?? Anyway, it runs well. Has Phil Wood hubs. What do you think? A good buy? Or an upgrade nightmare. I am mostly interested in the wheels. It has a 140mm rear hub. Would a 145 hub fit with no real problems?
Thanks in advance

1978 = 5 speed
1979 = 6 speed using narrowed flange hubs by Phil Wood

As for being a good value, it depends on what type of riding you plan to do. Santana's tandems -- and all others -- have changed a great deal (for the better) over the past 25 years. In fact, they changed a lot by the 90's.

As noted by Galen, you can have the rear triangle cold-set to 145mm by a good bike or frame shop. However, I would be mindful about how much I invested in upgrading the Santana as there will be a point of diminishing returns.

At $500 it is a decent buy, depending what you want to do. Ride it 'as is' or do minimal upgrading.
As a first time tandem it would be a cheap introduction into tandeming and you could always get most of your money back if you decide to purchase a better/later model 2-seater.
Phil Woods alone are worth 1/5th of the asking price!
Pedal on TWOgether!
Rudy and Kay/Zonatandem