The current version of SFI specification 2.3, designated by SFI as Specification 2.3U dated effective May 7, 2021 (hereinafter “2.3U”), provides in part as follows on page 24, section VI, “TUBING SPECIFICATIONS – FRONT HALF”:

At present, NHRA plans to amend the NHRA Rulebook for 2024 to provide that 2.3U will apply except that the “Tubing Minimum” for the front half top and bottom frame rails will be 1.25 x .058”. 

SFI and the SFI Chassis Advisory Committee are continuing their review of 2.3U.   For now, teams are being advised that they can purchase the necessary .058” raw material needed for the start of the 2024 season, but should not build any front halves for Top Fuel cars until further notification is published by the NHRA.