In 1990 Guild decided to break the Nightbird model line into more options, those being the Nightbird ST (Standard), the Nightbird DX (Deluxe), and the Nightbird CU (Custom). The Custom, is the only one of the three that’s really like any of the previous Nightbird models, with the ST and DX being more like a Les Paul Studio than anything else.

The description in the catalog from 1990 states that the Nightbird ST has a solid Poplar body, Mahogany set-neck & Rosewood fretboard, as well as a Schaller wraparound bridge, dual DiMarzio humbuckers (serial number "LH1000").

According to the often incorrect Guild serial number charts, exactly 20 Nightbirds DXs were made, of which only four were made in 1991, with the other 15 having been made in 1990. The serial number prefix for Nightbird STs is LCxxxxxx and the dates reported on the charts show only the following dates of manufacturing:

1990: LC000001 – LC000015 (15) 1991: LC000016 – LC000020 (4)

And aswell, exactly 20 Nightbirds STs were made, and once again only four of which were made in 1991, with the other 15 having been made in 1990. The serial number prefix for Nightbird STs is LBxxxxxx and the dates reported on the charts indicates the following dates of manufacturing:

1990: LB000001 – LB000015 (15) 1991: LB000016 – LB000020 (4)

Note that this is the exact same ratio as the Nightbird ST, which might contribute to the incorrect number theory.