(17 Jan 2017, 10:14 pm)South Tyne Lad wrote You cant, I believe the production line for original's has closed, There might still be some as Dealer Stock waiting for a buyer however.
MMC / MMCcity are now the only E400s available to order.
The E400H is still available according to the Alexander Dennis Website:
http://www.alexander-dennis.com/products/enviro400h/
Would be no good for the X21/X22 though.