In 1978 Bachmann released a Southern Pacific DaylightGS4 based on a design its parent company Kadar had been producing for Lionel just a few years earlier.
These early models were never known for being high quality as they had underpowered slot car style motors and gears which over the years have been known to crack and split causing the wheels to come out of balance.
Bachmann ended up making a fictional Chessie System variation Daylight in 1979 as part of their line up and this shared the exact same drive system as the regular one.
These early pancake drives have become known as possibly the worst HO scale drive system ever made.