Easy guys. Technically, the OEM axle nuts are TTY, and the official recommendation must be to replace them any time they are removed. But, my experience is that the OEM axle nuts (the multi-layer packnut type) are better at retaining torque, even when re-used several times, than the aftermarket solid type nuts when new. I've found that if the OEM style nut still looks to be in good shape, it generally is, and will retain torque well. The aftermarket style, I've had even brand new ones require regular re-torqueing.
I've seen this same pattern on a number of vehicles, including the contour. And in general I would rather reuse an OEM nut a few times, than use a new aftermarket nut.