I think they built ten . . . all different, shame they didn't build 15 and add a few more variations.
I only paxed in one once but it was pretty cavernous, we sat on pax seats on the ramp. Quite nice crew transport from what I gathered from colleagues who flew on 53.
Saw one in Gan with 3 Wessex onboard - that was impressive (in those days). They used to fly about 10,000' below us and about 50 knots or so slower (ish).