"The aircraft are undergoing comprehensive maintenance and inspection work at Marshall Aerospace’s facilities in Cambridge before being delivered in a baseline configuration that will allow Türkiye to integrate its own mission systems.
Deliveries are expected to take place over three to four years, with the first aircraft planned to arrive by the end of 2026.
The C-130J-30 is the stretched-fuselage variant of the C-130J. Its fuselage is approximately 4.6 metres longer than that of the baseline aircraft, increasing cargo volume and providing space for additional pallets, personnel or mission equipment...
TurDef has learned that some of the aircraft underwent centre wing box replacement after their retirement from RAF service. Those still requiring the procedure will receive new centre wing boxes as part of the programme for Türkiye.
The condition of the centre wing box will determine much of the work required on each aircraft and the duration of its maintenance. As a result, a standard turnaround time cannot be established for every airframe.
The aircraft will therefore enter Turkish service either with centre wing boxes installed under the current programme or with structures replaced after their retirement from RAF service. In both cases, the work is intended to provide the structural life required for their planned service with the Turkish Air Force...
RAF-specific mission equipment, cryptographic devices and other sovereign systems will be decommissioned and removed before delivery. This does not mean that the aircraft will be stripped of their core C-130J avionics. Instead, they will be returned to a baseline configuration suitable for the integration of Turkish equipment..."
Türkiye’s 12 ex-RAF C-130J-30s are undergoing deep maintenance, centre wing box work and configuration changes ahead of delivery to the Turkish Air Force.
turdef.com
Pointing to above post from last year. Looks like the DIRCM that was on some of the aircraft will also be removed.