Mercedes basically used the Nissan truck for their truck offering, though I think now they abandoned the truck thing via low sales (price).
My thought is, Merc pulled one apart to see if it came up to their standard, which it did, though the V6 offering did have quite a few differences..
Yes, the trusty Vigo is a well put together long-lasting ride, but the Nissan is well worth looking into, in my humble opinion....????