Well it must be aftermarket. All the Toyota grills I’ve seen are made of plastic. The plastic grills in good condition are just about nonexistent. There are some copies out of Thailand, not sure of the quality.
It was plastic. I saw a half of one for sale a few years back and haven't seen one since. I have a couple originals in good shape.
Can't say I've seen a chrome grille on these trucks before - got a pic? I've seen on the pre-75s they had a silver-colored grille, is that the one you're looking for? Lastly - your profile description says you have a 1973, but you're seeking a 75-78 grille - you are aware the pre-75 trucks have a different grille than the later years, correct?
The truck in my profile picture is a 1973, restored with a 1975-1978 front end. My dad restored it in the 1990s and put a chrome grille on it. The entire front end is different 1973-1974, and I have an NOS 1973-1974 grille. If I can find a chrome grille, I'm restoring it with the later style front end like my dad did, but if not I've got the earlier parts to do it that way as well.
Ah I get it now. Grilles are hard enough to find, you likely won't find the chrome one -- I'd look into alternatives if you have some spare grilles to tinker with. Call up some shops that still do chrome plating ($$$$) and inquire. I suppose you could paint it with chrome spray paint, I think Krylon makes one for plastics. Another option might be that chrome stretch film
I saw a half of a chrome grille sell on eBay within the last year, so I thought I'd do a little digging first. You can find repop grilles fairly easily from overseas. The next step would be to get one of those and start making phone calls. Every now and then an NOS 1973-1974 grille will come up for sale. Think I gave $200 for mine from Thailand.