From observations I have noticed several buses still with the original interior, which is incredibly outdated - so here is a list of them for anybody trying to keep track...
Original:
Commanders:
1401* - 1403*
VDL Pulsar 2s:
1407/1409/1410/1414/1417/1418/1420 - 1428
MPDs*:
1759/1760/1769/1791/1800/1801
Solos:
2801/2802/2809/2810/2812 - 2825/2827/2828/2830/2832 - 2851
Deckers:
7445*/7446*/7453 - 7456
* Unlikely to be refurbished...

Inter-Urban:
VDL Pulsar 2s:
1429 - 1439/1444 - 1464/1467 - 1478/1484 - 1492/1494/1497/1499/1508 - 1511
MPDs*:
1766 - 1768/1773
Solos:
2601 - 2603/2852 - 2871
Volvo B10/ALX300s*:
4516/4523
Deckers*:
7484 - 7494

In terms of Double Deckers, refurbishments aren't necessary as it seems they are used on School work most of the time. And most Double Decker vehicles in the fleet are either MAX or Sapphire...

Also for anybody wanting photos of the original livery buses, before they eventually disappear from the North East...

Original Livery:
1407/1409/1410/1414/1417*/1418/1420 - 1423/1769/1791/2809/2812/2813/2814/2818 - 2820
1417 is apparently getting repainted into the new livery atm.