At it's peak, Sudan's military had over 60,000 troops and the SPLA mustered over 50,000 fighters. The government has had to institute several drafts in recent years and would probably welcome demobilizing several thousand soldiers simply for economic reasons.
However, an accurate count of the rebels' current strength levels is as much a matter of propaganda as operation security. It is to the SPLA's advantage to inflate while the government downplays rebel numbers. Accurate figures for the other groups are also impossible to calculate, due in part to the fluctuation of core members and 'part timers' who only turn out for operations or raids. Another factor in Sudan's civil war is that alliances shift both inside of rebel groups and with the government, with groups disappearing or change sides on their commanders' whim. The result is a political kaleidoscope that, if not defused during the current peace negotiations, could result in an entirely new set of rebel groups.
In addition to the southern-based rebel Sudan Peoples Liberation Army (SPLA), there is also the National Democratic Alliance (NDA), an umbrella of northern rebel groups. The Darfur-based Sudan Liberation Army (SLA) rebels emerged in February 2003 and massed about 2,000 fighters during it's larger raids in October.
The Umma Party (one of the Islamic rebel groups in the north) signed a peace agreement with the government in July 2002. In January 2002, the SPLA merged with the Sudan People's Defense Force (SPDF), which had split from the SPLA in 1991 amid factional fighting. - Adam Geibel
With peace about to break out in the Sudan, one of the implied problems will be finding gainful employment for the various rebel fighters and government troops no longer needed to fight them. One has only to look to the Congo or Liberia to see what chaos can erupt if a thorough disarmament program isn't part of the peace planning.