Note that the ground clearance is a lot less. In the past, Lexus specs are more accurate than Toyota's. BUT, you have to compare tire sizes b/w the two. The underbody should be the same...as is the rear axle. The major difference underneath b/w the two is the lack of transfer case (i think) in the GX. But, transfer case is rarely (if ever) the lowest point underneath on any truck.
The 4runner Trail is probably the highest standing 4runner...but KDSS option does lower the effective ground clearance i believe by a bit. So, keep that in mind.
You may want to ask the 5th gen forum for more real-life info.