Two of the four prototypes (11601, 11602) were built with a split locomotive body, whereby the joint may only move on an horizontal transverse axis to allow for changes in gradient, similarly to the Rhaetian Railway Ge 6/6 II.

[1] The other two prototypes (11603, 11604) got a softer secondary suspension instead of the joint, which proved to be so reliable in everyday use that all other locomotives of the series were built this way.

The exterior design is similar to the Re 4/4II (Re 420), as are the driver's controls and the conventional transformer technology with fixed running notches, which was applied for the last time for this locomotive.

Such a couple, often referred to as "Re 10/10" (both locomotives are Re class, so the couple is Re class; 10/10 means that they overall have 10 driven axles out of 10), is capable of pulling the maximum train weight of 1,300 tonnes (1,300 long tons; 1,400 short tons) on 2.6% gradients of the Gotthard line.

On 1 January 2003 they were exchanged against the Re 460, meaning that now all remaining 88 locomotives were assigned to SBB Cargo.

Due to the reassignment of the Re 460 to the passenger division, the Re 6/6 again dominated freight traffic on the Gotthard line.

The following table lists Re 620 locomotives with their number, commune names and respective coat of arms (COA).