Yes - the difference is really quite dramatic.
Here's the change in dimensions from the standard length GTR to the Longtail - much greater than 6 inches, try 22.3 inches with most of it at the rear.
4933 mm (194.2 in)
4367 mm (171.9 in)
I was very fortunate to see 6 of them racing together in the FIA GT series back in 1997 at Laguna Seca - great memories of that day!
Here's some fresh photos of this one taken last week at Laguna Seca by the guys from MotorTrend magazine which were shared on Instagram.