A 7000 series with a V12 would have come with a Clark 400 Series 5 speed transmission. It was a synchronized transmission with positive lubrication to the main shaft to keep it lubricated during long periods of time in a straight through gear. Spicer 5 speeds would not hold up to the high rpm and torque of the V12. You must keep in mind they went up to 275 HP @ 2400 RPM It could have had a Spicer auxiliary behind it or a 2 speed Eaton axle.