Hi Ray,
There were a few US models in 1958
Skyliner - Hard top retractable- cool car
Fairlane 500 -in 4 door and 2 doors etc.
Fairlane- same as above but different trim
Custom 300 style tone - shorter chassis than above and different trim
Custom - this was the entry level model same shorter chassis
(quite a few different chassis were available, ranchero, ranch wagon and convertible
The 300 only stood for the body model, engines available ranged for 6 cylinder to Y block 272, 292 and big block 332, 352 and 361

Thanks for the interest
Cheers