I wouldn't expect them to be really high on the miles,
With aged aircraft such as these Saabs, mileage (number of hours) is not the issue. It's the number of cycles that you've got to look out for as they have the greatest bearing on aircraft maintenance due to the constant pressurisation/depressurisation and takeoff/landing stresses the components undergo. This is especially true of regional aircraft as they operate in low flight hour:high cycle environments with up to 10 sectors (and therefore cycles) a day.
You typically see landing gears overhauled at the 10 year mark. It won't be long before these Saabs face their 2nd gear overhaul.
In addition to the aforementioned P-3s, C-130 FLIR, Saabs and what not, let us not forget the pair (?) of King air Beechcraft equipped for ISTAR duties.