differences between LWB and SWB when converting...

[tripleblack]

I am sorry about the redundent question, but i want to convert my LWB to a SWB. I have been told in the past by board members that i must get the right frame,suspension, driveline, trailing arms and bed and everything else swaps over. I am okay with that. But just out of curiosity, i would think that the only differences between the two would be the 8 inches off of the end and 12 inches off of the middle part of the frame (and moving the cab mounts 12 inches back), of course the length of the bed and brake cables/wires, and lastly the length of the driveshaft. As far as suspension and trailing arms, i am confused as to why they would be different. Can someone please explain if this is even true and why? Pics would help also. Thanks for the help.