After install the CC860S were about 2" taller than the CC880. From the CC880S to CC880 I lost 1" so I guess the CC860S is 1" taller than the CC880S on my van with the 5.4l. On yours with the extra weight of the 7.3 you may get the same height with a softer ride. All this dimensions are once installed on my van. Here is a table. I think what is listed as install H is under the listed load.
View attachment 601631
As for spring rates, On the CC880S it compresses from 16.6" to 12" under 3006lbs, the spring rates should be 3006/4.6=653.4 lbs/inch and the CC860S is 1797/3.27=549