The 540RHH was changed multiple times. In 1991 the Lo-Pro Edge tremolo was introduced and was used on the 540RHH along with the Edge for the Japanese market. In 1990 the pickup selection toggle moved from between the two pots to a spot closer to the volume pot. The JS models based on the 540RHH do have the toggle on the older spot.
The 540R is a similar model with a humbucker/ single/ single pickup configuration.
Specifications for 540RHH
Model name: 540RHH / 540R-HH
Year(s) produced: 1988–1992
Sold in: Worldwide
Made in: Japan
Finish(es): Black (BK) 1989–1992 / Candy Apple (CA) 1992 / Crystal Pearl (CP) 1990–1992 / Jewel Blue (JB) 1989–1992 / Jewel Red (JR) 1988–1989 / Ruby Red (RR) 1990–1991 / White (WH) 1990–1992