We currently use UPS for most of our shipping. We usually like to ship 3-day because it allows you to know exactly when the package is slated to arrive, yet it is rather inexpensive. Basically, it all depends upon when you want your order delivered. We can usually ship most orders the same day, although some parts require special packaging.
New parts are easiest to ship out, since they are easy to pack.
Used parts usually require us to confirm that the part meets our high quality standards prior to shipment. Used parts are usually shipped the same day, although some need too much time to package and need to be sent out the next day. We sometimes prefer COD, although sometimes people don't ever pick up the packages. For Canadian customers, we ship either UPS or US Mail to Canadian Mail. UPS charges hefty customs fees when packages cross the border, so we don't recommend that anyone send packages via UPS to Canada.