Looking to buy, gonna decide this week. Thanks to those who have offered advice so far. Here is what I am looking at. My primary concern is reliability.

S80
2001 T6 Exec 63K miles, all service records available, $12,700- Volvo dealer
2000 Non Turbo, 72K, no records, $13K Carmax
2004 Non Turbo, 63K, no records, $12K Indy used lot

S70
2000 Non Turbo, all records available, 85K miles, $9K Volvo dealer

All cars have a clean carfax.

Questions:
1. What do I look for in the records to indicate a problem car?
2. Which is considered more reliable, the 00-01 S80 or the 00 S70?
3. When was the tranny issue in the S80 fixed?
4. What can I look for to indicate a TB issue since that seems to be the biggest issue on these cars?