Ferrari have parted company with chief designer Nikolas Tombazis and engineering director Pat Fry, two of the men responsible for designing this year's car as the team endured their first season without a win since 1993.
"James Allison ... will be responsible for all technical aspects of delivering drivers Kimi Raikkonen and Sebastian Vettel, as well as newly appointed test driver and third driver Esteban Gutierrez, with the most competitive Formula One car possible."
It has been a period of upheaval at Ferrari after Marco Mattiacci's brief reign as principal ended at the end of November. The troubled Fiat-owned outfit replaced him with Maurizio Arrivabene, the team's third boss in nine months.
The glamour team ended the season in Abu Dhabi without a single race win and the conclusion of the campaign also saw the departure of double world champion Fernando Alonso.
Germany's four-times champion Vettel has been signed from Red Bull as the Spaniard's replacement.
Long-serving president Luca Di Montezemolo, a link with the team's late founder Enzo, also left Ferrari last month.
He has been replaced by Fiat Chrysler chief executive Sergio Marchionne.
Image: Ferrari Formula One driver Fernando Alonso of Spain steps out his car following an engine failure during the Italian F1 Grand Prix in Monza.
Photograph: Max Rossi/Reuters
Formula One: Stolen Red Bull trophies found in lake
Feels special to be part of the Ferrari legend: Vettel
Hamilton takes second F1 title in style
McLaren name Alonso, Button as their F1 drivers for 2015
Red Bull factory raided, F1 trophies stolen