I have a '84 Jimmy with a 400 smblock motor built up a bit to about 360hp, a 700-R4 tranny with NP208 T case. I will be using a D44 front and 12" corp. rear ends. I plan on upgrading the gearing to 4.56 with an ARB locker in the front. My question is, what will passing gear be like on the highway at say 60 MPH? Seems like my RPM's will be WAY UP THERE! Does anybody have this set-up and can attest to what the highway driving will be like?