What we're trying to say is the hi pinion is designed to be used in the front axle only. The standard (in this case v6 'low pinion') diff was designed to run optimally in the rear axle. In those applications they each are running on the drive portion (not the coast) side of the gear set, and are properly lubricated. When you run a standard diff up front and a high pinion diff in the rear, both are operated (torque is applied) on the weaker coast side of the gearset. The hi pinion isn't lubed properly running that way. Lube is not so much an issue when a standard diff is used up front as the pinion shaft and gear is down in the oil reservoir.
Beyond that, Toyota 8 inch diffs are really strong for their size and weight. Think of them as a mini 9 inch Ford.
