The two trucks are "nearly" exact twins... BUT, the 250 is rated and tagged as a 3/4 ton vehicle and the 350 is rated and tagged as a 1 ton. This is the reason for the difference in the GVWRs. In the east as well as some places across the country, many of the local roads are restricted by vehicle capacity. Where I live, there are signs that prohibit vehicles above a 3/4 ton rating, from traveling on many of the local roads unless they are there to deliver or pick up from an address that is on that particular road.
I can travel these roads in my F250, but a friend with his F350 can not do so unless he wants a hefty citation for his trip.
The variation in the 4X4 and 2WDs is due to the difference in the weight of the added drive train in the 4X4. Thus the reason for the difference in payload.
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