The RG7421 is a similar model with a fixed bridge. The RG7420L is a left-handed version.
The original RG7420 had a production run of three years, but in 2013 model year, an updated model was reintroduced with the same model number.
On occasion the 7620 and 7420 are mistaken for each other. If you take the necks off of a 7420, many times they used the 7620 neck for both guitars and are marked as such. This adds to the confusion. The 7420 uses the Lo-trs tremolo. It's the easiest way to tell which guitar you have.
Specifications for RG7420 (2000–2002)
Name: RG7420 / RG7-420
Made in: Japan
Finishes: BP (Black Pearl) / CB (Cosmic Blue) (2001) / MC (Magenta Crush) / NB (Northern Blue) / RBF (Royal Blue Flat) (2001–2002)