Teaser 2826: By heck!

From The Sunday Times, 20th November 2016 [link]

The registration number of my old car consists of three consecutive letters of the alphabet in reverse order, followed by a three-figure number consisting of the same digit written three times, followed finally by a single letter.

I am a fan of “hex” (i.e. arithmetic in base 16, with “digits” 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E and F) and I realised that the registration number looked like a number in hex. So I worked out its equivalent value in our usual base-10 arithmetic. Miraculously the answer was a nine-figure number that used all nine of the non-zero digits.

What is the registration number?