"... hoping ... clarify as to why ... 74 ... a split rudder ...?"
TBC design history may reflect their lessons from "discrepant rudder" fatal mishaps.
B307 Stratoliner had a fatal upset on 18Mar39 (single Rudder).
B707 had two fatal discrepant rudder upsets (Single Rudder). [Crew trainer 19Oct59 B707 N7071
, & AA Flt One / 1Mar62.] Much later: WAL366, a B720, at ONT of 31Mar71, failed Rudder Control System (fractured Support Fitting for the Rudder Hydraulic Actuator; due to high tensile loading and stress-corrosion cracking). The "artificial feel" mechanism (included in the rudder control system) masked this failure from the crew during their yaw/roll upset.
Recall that Bill Cook invented Boeing's "Yaw Damper" for the XB-47 project (see _Road to the 707_, pg181+).
TBC seemed to forget lessons learnt from the XB-47 project, the initial B707 lacked both Rudder boost and the (artificial S&C) Yaw-SAS. As always, the new engineered-safety-feature (Yaw Damper) introduced new failure-modes: that fatal rudder-Y/D-softover aboard AA Flt One 1Mar62.
So, after early S&C mistakes on the B707 model, the B727 was introduced (FF=9Feb63) with an Upper and Lower Rudder, and a separated "Yaw Damper" for each Rudder [B727-100 was undamped and divergent above FL260 without that artificial S&C addition].
B747 FF = 9Feb69, and B747 had two Rudders:
Yaw Damper 747-400
[some mishaps cited and some history on split-rudder].
Woooo!!--> There's a whole TV show on B747 discrepant Rudder:
Later, around 1982 during testing on the B767, even the short body B767-200 was much less prone to "dutch roll" at very high altitudes (a surprise test condition at FL450 convinced me that B767 had much better "natural" damping and B767 was a big improvement over B727's "undamped & divergent").