Fender Vintage Part from 1978 Stratocaster Tremolo Block

Fender Vintage Parts from 1978 Brass Work Series. Fender Stratocaster Tremolo Block out of solid brass.
This is old stock from my Fender collection. Comes from the german Fender distributor back in the late 70's. Fender USA part
Material: solid Brass - very massive

[mutantbaby]

In what year did Fender start using brass? I like the sound of brass blocks but it changes the sound so much it's like a different guitar.