I'm going to have a guess and this is how they will be numbered. Links to are to photos of them working with First.

5511 SM13 NBA Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First Someret and Avon, Fleetnumber 63070.
5512 SM13 NBB Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First Somerset and Avon, Fleetnumber 63071.
5513 SM13 NDK Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First South Yorkshire, Fleetnumber 63002.
5514 SM13 NDL Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First South Yorkshire, Fleetnumber 63003.
5515 SM13 NDN Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First South Yorkshire, Fleetnumber 63004.
5516 SM13 NDO Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First South Yorkshire, Fleetnumber 63005.
5517 SM13 NDU Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First South Yorkshire, Fleetnumber 63006.
5518 SM13 NDV Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First South Yorkshire, Fleetnumber 63007.
5519 SM13 NDX Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First South Yorkshire, Fleetnumber 63008.
5520 SM13 NDY Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First South Yorkshire, Fleetnumber 63009.
5521 SM13 NDZ Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First South Yorkshire, Fleetnumber 63010.
5522 SM13 NEF Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First South Yorkshire, Fleetnumber 63011.
5523 SM13 NEN Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First South Yorkshire, Fleetnumber 63013.
5524 SM13 NEY Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First South Yorkshire, Fleetnumber 63016.
5525 SK63 KHF Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First South Yorkshire, Fleetnumber 63029.
5526 SK63 KHG Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First South Yorkshire, Fleetnumber 63030.
5527 SK63 KHL Wright Streetlite DF Wright Streetlite Max N – Not In Service (Reserve) Go North East Roadstripe Livery No No New to First South Yorkshire, Fleetnumber 63033.