Looking for anyone who has made this swap or similar swap in older Dodge pickups. Right now we're running 360 CID V8 built for torque with an old granny 4 speed. Do you have to have an adapter to put Dodge model NV 4500? Axles are Dana 60 Front and Rear with 4.10 gear ratio. Truck is turning around 2400 RPM's @ 45 MPH. Tires are 33"X 10.5", will be switching to 37"x12.5". Can someone tell me what the difference would be on speedometer and approximate RPM's with 2" tire circumference @ 45 MPH. Any help would be appreciated. Rick