I think the plastic thumb rests are totally ridiculous... especially if you're paying more than $1000 for the bass.
I always replace mine with either an ebony or rosewood one.
Did Fender always make these out of plastic? Fender historians? ...got any answers for us?
Official Fender Precision Bass Club member #223
Fender 1963 AVRI Precision Bass
Fender 1962 MIJ-RI Precision Bass