The prototype had two 180 hp (134 kW) Lycoming O-360 engines, a fixed nosewheel landing gear and a Cherokee Six vertical tail.

The second prototype flew on 30 August 1968, still with the 180 hp (134 kW) Lycomings but had retractable landing gear and a taller vertical tail.

The third prototype was closer to the production standard and flew on 20 October 1969; it was fitted with 200 hp (149 kW) Lycoming IO-360-A1A engines.

[6] The new model incorporated changes in the aircraft's control surfaces, including enlarged and balanced ailerons, the addition of a rudder anti-servo tab, and a stabilator bobweight.

[4] The "T" in the new model designation reflected a change to turbocharged, six-cylinder Continental TSIO-360E or EB engines for improved performance, particularly at higher altitudes.

The new aircraft also incorporated a one-piece windshield and a bare metal instrument panel instead of one covered with a removable plastic fascia.

This model was similar to the Seneca III offering minor improvements, such as a streamlined engine cowl for increased cruise performance.

Again the cowls were redesigned for increased performance, several cockpit switches were relocated from the panel to the headliner, and an improved engine variant, the Continental TSIO-360-RB,[6] fitted with an intercooler, was used.

One notable civil operator is Eid Air Aviation,[11] a flight school located in Bromont, Canada Data from Piper Seneca V Information Manual (October 25, 2005)General characteristics Performance