Hi Jay, most of the ones you find in the aftermarket are probably going to be made to use with electric fans (like the one I use). But you can make your own. I've seen this done a couple of ways. One guy used a commercial sized cookie sheet (which he cut the edges off of). It fit on his radiator support and then he cut a fan hole and used common galvanized metal to make a tunnel which he had riveted to the cookie sheet. It wasn't what you'd think the factory added. Still I thought it was a clever thought and painted black it wasn't terrible. Another guy had torn apart a gable ventilator (which had close to the right size of the tunnel his fan needed) and had mounted that to something I wasn't able to identify (could have been fiberboard or that stuff used as shower walls). That one worried me, but the tunnel part looked pretty good. Here's the ventilator type I'm talking about:
https://tinyurl.com/y99eat2n If he had mounted that on something like the cookie sheet I think he would have been ok. Good luck.
