Just for additional reference I am running a 3.43 rearend in my 49 with a 350V8 and 350 Turbo transmission. At 65mph the tach reads 3200 rpm which I feel is too many rpm for a long highway trip. In April I will install a 2004R overdrive tranny and the rpm should drop to about 2000 at 65mph which also should give me better gas mileage.