after burning a valve in my rebuilt 18R-G i went into the shed to dig up an old 18R-G head i have had for a few years now, and had been trying to sell for $100 or so..i looked at the valves and they had TRD stamped on the bottom of them..i thought ohh yeh, what ever..then today when i got the head out if the shead
SHOCK HORROR!!
on the back of the head there is a TRD stamp part number B1113
just asking if anyone knows what this means!! obviously it's good, but how good?