Your 6.17 rear will probably hold up just fine, however you might end up holding back lots of angry motorists. You will want 1800 to 2000 RPM at your cruise MPH, so gear accordingly.
Ed
Hi Ed, sorry for the dumb question, but English is not my native tongue so I don't always understand. what do you mean by gear accordingly, are you saying I can change the gear ratio of the differential?
