It's just 2 resistors and LDR but it's a expert hack.
I have buy Japanese LDR on ebay: 170591651013
Part number is P1241-05
Hacks électroniques et radioamateurs par Nicolas F4EGX
Here are all the details of the MD380 screen backlight hack
Open the MD380
On the front Board, between two connectors, you have a little group electronic components.
Remove a 2,2k SMD resistor which is located between the two transistors.
220k = Slight attenuation of the screen
270k= attenuation of the screen perfect for me
330k= Black screen on the night (see nothing, on the night)
Solder 270k smd resistor instead of the 2,2k
Add 2,2k resistor
Make a 4,5mm hole for the LDR near Speaker and mike
push the LDR on the hole, glue
This is the front board with 270k // (2,2k + LDR)
2,2k in serial with LDR
Couple 2,2k and LDR in paralelle with 270k.
Add black adhesive on back side of the LDR (very important)!