Yes, an LED upgrade is available for the Sandel SN3500 EHSI.

Certain original production units of the SN3500 do not include the LED backlight. The upgrade incorporates an LED backlight with 10,000 hour minimum MTBF. Sandel offers the LED upgrade for various prices. $1500 if the unit is under warranty and $2000 if it is not under warranty. Units with serial number format of 5-XXXX were manufactured with the LED already incorporated.