If you've tried fitting LED bulbs to your T3 (or in fact, Caddy, LED etc.) you'll have discovered that the indicators don't work correctly.
This is due to the fact that the flasher relays rely on a resistance from the bulbs to work. LED bulbs give very low resistance so they don't flash with a standard flasher unit.
Its a properly developed item and will work in early and late T3 fuse boxes - bullet and blade fuses.
Its not a modified relay with resistors soldered in!
Simply unplug your existing relay. Fit your LED Indicator bulbs, and then fit this relay.