Maintenance and conversions of old models

A bunch of reasonably recent and modestly popular jets:

Super DC-8:

DC-8-61 78 passenger frames, 10 new freighters (convertible) – 88 total
DC-8-62 51 passenger frames, 16 new freighters (convertible and pure combined) – 67 total
DC-8-63 41 passenger frames, 66 new freighters (convertible and pure combined) – 107 total

262 new Super-DC-8 combined – last delivery 1972.

Reengining offered 1982-1988. Total conversion:
DC-8-71 – 53/88
DC-8-72 – 7/67
DC-8-73 – 50/107

Observe that DC-8-71 conversion is harder than the other two because it includes changing the wing.

Tristar:
Tristar 1 – 160 frames
Tristar 100 – 15? frames
Tristar 200 – 24 frames
Tristar 500 – 50 frames
total 249
last delivery 1983
Conversions:
Tristar 50
Tristar 150
Tristar 250

DC-10:
DC-10-10 incl. -15 – 129 passenger frames, 8 new (convertible) freighters, total 137, last delivery 1983.
DC-10-30 – 169 passenger frames, 37 new freighters (convertible and pure combined), total 206, last delivery 1988.
DC-10-40 – 42 frames, last delivery 1983
KC-10 – 60 frames, last delivery 1988

MD-11:
136 passenger frames, 64 new freighters (convertible and pure combined), total 200, last delivery 1998

A310:
255 frames, last delivery 2007

A340:
A340-200 – 28 frames, last delivery 1998
A340-300 – 218 frames, last one (Burhan) delivered to VIP (Alisher Usmanov) in May 2012, last airliner delivered 2008 (to Finnair)
A340-600 – 97 frames, last delivery 2010
A340-500 – 32 frames delivered, 2 still under construction – no new orders accepted after late 2011.

So… considering the examples of DC-8 etc., what are the A340 frames good for?