Hi. New owner of a F250 CC SB 4x4 and new to the site. I was curious about the GVWR of the F series. I called a dealer about rear springs for a F350 and was told that they are the same part# as the rear springs on the F250. I was also told that the only difference is the F350 has a 4" block vs. a 2" block on the F250. If this is the case, how are the GVWR different? It seems like I'm overlooking something simple that will have me slapping myself.