Or any other post I see that has a person with a class and X with a number. They have leveled to a specific level but arent being very specific about it? (like 7x means level 70 something).
Or is it they have leveled a character to max that many times?
You dont have to be a nuker class to get 1lvl/day past lvl 60 :P
Although some classes are easier than others (like nukers as you mentioned)
Good connections help too.
Some groups are better than others.
Having uber gear also helps alot.
Having all day to play is even better.
As for a BD, after 58 he can join and is wanted in every group. The higher the mates, the higher the risk, but depending on the group the exp is still faster then everything else. SwS for example are good after 55, we often had a lowbie sws with us while doing some nice aoe in fog (the beetles are soooooo nice to aoe ^.^).
Prophets also lvl very fast after they got their buffs. As I rejoined L2 in C3 I freshly started the prophet and everyone around was like 40-50. After I was was 40+ they were 60+ and now some of em are 78, some are 75 and im also 75.
Play a support class or a "I-can-solo-till-75" class, 1 lvl past 60 is easy.
Since your are a sorc (@Allwine) you got some good aoe spells, try to get into a aoe party. Around your lvl AL should be nice. Grab 2 Poles, 1 or better 2 Healers and a buffer and clear the $room. You can lvl there all way to 75 (on 74 (or 73?) the first mobs start to turn light blue, but down worry. $room +ramp and if with strider a bit from karma room direction are still fast exp ^.^)
edit: Just in case someone whant to compare, I was going through some old screens. I found one where I was 71, gettin 5949, 8550, 7425, 6111, 6822, 7935 exp (5ppl party, all about same lvl). Not sure what is what (5k is obvious Pytan Knight, 8k could be Pytan and 7.9k Limal, the other are the Malruks then.) A party of 5 that is used to it can clear the room with 2 pulls.