Originally Posted by
Vintage_Cyclist
An 84 serial number would be the year the frame was made. It wouldn't be unusual for an 84 built frame to be marketed as an 85 bike.
The pictures above show a Cyclone MKII front derailleur, but a Superbe GT rear.
If the picture in the '85 catalog is to be believed (and I think it is), they changed the color of the Sequoias that year. The '85 catalog says the Sequoia is "Slate Blue Metallic" and the picture shows a fairly gray (slate?) looking frame. The earlier Sequoias, like the OPs, are more like the "Medium Blue" Rockhopper pictured in the '85 catalog.
Not having seen an '84 catalog, I don't see any reason to think the OP's bike isn't an '84 with the same components as an '85. Maybe they all had these, maybe they transitioned later in the year. Who knows?
I agree that Superbe GT rear derailleur is a nice item.
Edit: looking at the color again, I could be wrong. Lighting variations could be tricking my eyes.