2-8-8-4 wheels. The locomotive's superstructure was attached to the rear group, while the forward group and leading truck could swing laterally on curves. All Yellowstones had fairly small drivers of . (For greater speeds, the Union Pacific Railroad chose a four-wheel leading truck and drivers of for its Big Boy 4-8-8-4 class.) Several classes of Yellowstone, especially the Duluth, Missabe and Iron Range's locomotives, are among the largest steam locomotives, with the exact ranking depending on the criteria used. The Northern Pacific Railway was the first railroad to order a 2-8-8-4. The first was built in 1928 by American Locomotive Company;
How 2 was featured on the "30 Years of CITV" documentary that aired on ITV on 29 December 2012 and featured interviews with Dinenage and Jones. The last episode of the series was a 30th anniversary special. Before that, there was "The Best of How 2" which aired on 18 August 1997. There was no series aired in 1998 but there was a spin-off series called "How Goes 2", which aired from 25 February to 15 April 1998. The series focused on Fred and Gareth going to different places each week, and the 8 shows featured segments from the first 6 year