the 1984 Monte Carlo SS only had a 305... unless you bought the one made in Mexico

In Mexico, in 1984, and only 1984, you could have purchased an SS with an LM1 350 V8 and a 4 barrel Rochester Quadrajet hooked up to a 4 speed manual gearbox. Not only that, but the Saginaw transmission also came equipped with a Hurst shifter. Other variations from the American version included the elimination of the SS rear spoiler, different side graphics, checkerboard style wheels, different mirrors, special steering wheel, no center console, only power locks, only manual windows, and the interior was styled using Pontiac Grand Prix parts rebranded with the SS logo.

https://www.streetmusclemag.com/news/this-aint-no-chupacabra-but-its-just-as-rare-the-mexican-monte/

The regular Monte Carlo came standard with a 125 hp 229 CID V6 (231 CID V6 for California) and a 165 hp 305 V8 was optional.

 Available for the last year in a base Monte Carlo was the 350 CID diesel engine, and there were only 168 manufactured.

All engines for 1984 got the three-speed automatic transmission with the exception of three SSs at the end of the 1984 production run that received the Turbo Hydramatic 200-4R transmission with overdrive.

https://en.wikipedia.org/wiki/Chevrolet_Monte_Carlo