I‘ve just put in a 12 % longer 5th gear in one of my stock engined Panteras. This is the way it should have come as stock. Relaxed cruising, less noise and better fuel consumption is what you get. My other Pantera, which will have a slightly tuned engine, will get the 3,77 crown and pinion. In my humble opinion the Pantera can handle much longer gearing than we think. Donˋt forget to factor in tire circumference in your calculations.