I don't have the length, but the F-150 shock had to be fully compressed
to get it on the back of the Kick, and the Crown Vic shock works perfectly
with my 3" lifted springs.
I looked up 3 different lengths, depending on the type and year of the F-150,
starting at 26, 24 and 22, extended length, so I would measure your normal
ride height and pick a shock that is in the center of it's stroke for the length
you need