It should work if the valving is right.
On the IFS...even the stock shocks are long enough for a lifted truck....so correct...even a 3" uses the same length FRONT shocks.
For the rear...16" compressed should be OK...and the 27 extended will be fine for stock springs with longer shackles...even 26" is enough for most people there.
If the site lists the valving...or you can call them and ask, etc....it would help.
Ball park, for a X with typical skids/sliders and a fat driver...etc...something like 255/70 - 275/80 valving is great....see how close the shocks you are considering come to that range. (The higher numbers are firmer, give tighter control/ride harder...the lower numbers are less firm, are more wishy washy, and ride softer...)
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- TJ
2001 Xterra '03 VG33, SE 5 spd, 305/70/16's, Revolvers, UBSkidderz, Doubled AAL's, 3"SL/2"BL, winch/bumpers, skids, sliders, OBA, Snorkel, pine stripes....
Friends don't let friends drive stock.
http://www.gifsoup.com/view/501230/tj-tackling-crawlers-ridge-o.gif