Does a Durango count as 1/2 ton - probably yes. Anyhow here's my experience:
Gen 1, 5.9 @5500#: good tow on hilly interstates Gen 2, Hemi @ 5500#: easy tow on hilly interstates Gen 2 Hemi @ 8500#: OK tow with straight hitch and surge brakes. Would be good tow with weight distributing hitch and electric brakes.