Uniden 68 elite

By dual system, do you mean two antennas or that the antennas are also used for am/fm radio too? If the antennas are dual purpose, consider using a single setup for each. Wilson Silver Load or Firestick antennas are good choices, fairly inexpensive and work well. both are available with swr adjustment feature that doesnt require trimming. Look for a co-phase harness made from Belden cable if you run two antennas. Or you can just run one antenna if you want, with a single co-ax. The dual setup offers a little better performance, but not a huge difference. A single setup will save you a few bucks and is simpler. Buy a good mount, stainless if you can find one.

 

I would go with a 5 foot fiberglass dual phase antenna, as this may give you better reception.