Nope, that should be all that you need.
If you have an electronic speedo and you disconnect the harness from the ECM, your speedo might not work since the VSS sender goes through the harness to the VSS Buffer then to the speedo cluster.
I made the mistake of cutting off the harness and having to figure out how to wire the sender straight to the buffer. Pete helped me with a tech article showing the wire color codes and where they go.
'86 Pontiac Trans Am WS6, LG4 305, 5 Speed, CF DF Clutch,
Edelbrock 1406 Carb, Edelbrock Performer RPM 7101 Intake Manifold.
Edelbrock Open Element Air Cleaner: Flowmaster Exhaust, 160* Thermostat,
Grant GT Steering Wheel, MSD HEI Coil, Taylor 8mm Wires, Leather 96 Camaro SS Seats,
Alpine CD+Changer,Alpine V12 Amps, Premier TS-1040C Subs, Polk Audio highs/mids.
Best ET: firstname.lastname@example.org
High Speed Run: 157mph WS6 Trans Am