According to Av Consumer's Used Aircraft Guide, the Warrior began replacing the Cherokee 140 in 1974, though both were offered for a while.
I don't think it's fair to say that the Warrior "replaced" the Cherokee 140. They were for different markets. The Cherokee 140 was basically a two-seat trainer with a couple of snap-in temporary seats in the back, while the Cherokee Warrior was a full-size four-seater intended to compete head-on with the C-172. Cherokee Warrior was introduced for the 1974 model year, and the Cherokee 140 remained in production through the 1977 model year, after which it was replaced by the Tomahawk as Piper's trainer.
The significant initial differences were that the Warrior had the tapered wing and an 10 extra HP.
As John mentioned, the post-1964 140s and the early ('74-'76) Warriors had the identical 150 hp O-320 engine -- common also to the earlier "Cherokee 150".
But there were many other significant differences between early Cherokee Warriors and their contemporary Cherokee 140s. From the get-go, Cherokee Warriors had the elongated fuselage introduced on the Cherokee Arrow II in '72 and on the Cherokee Challenger (180 hp) and Cherokee Charger (235 hp) in 1973; as well as larger stabilator, full-size rear bench seat, baggage compartment with baggage door, different cowl and smaller nose wheel. The Cherokee 140 never got the fuselage stretch or larger stabilator (it was the only model with the original PA-28 dimensions after 1972), and it never had a baggage door or full-size baggage compartment.
Assuming this is correct, there are no Hershey-bar winged Warriors out there.
There are no Hershey-bar winged Warriors out there. The first Cherokee Warrior (1974 model year) had the tapered wing, and it was the only model with tapered wing until the 1976 Cherokee Archer II.
Again from Av Consumer, the Archer nameplate replaced the Cherokee 180/Challenger nameplate in 1973, with the airplane wearing Hershey bar wings until 1976. So there are both style wings out there with Archer branding.
With the change to tapered wing for the 1976 model year, it was renamed "Cherokee Archer
II".
The "Cherokee Challenger" and "Cherokee Charger" nameplates lasted only the 1973 model year, then were changed to "Cherokee Archer" and "Cherokee Pathfinder", respectively. I'd heard that came about because Chrysler Corp. squawked about use of their muscle cars' nameplates.
The name "Cherokee" was dropped after the 1977 model year on all PA-28s. There was a "Cherokee Six" for 1978, but for 1979 it was just "Piper Six 300".