If I understand correctly and you’re looking for a used OE Set, I still have my original covers, removed now in a box from my 79/2 40. They’re better than the ones in the pic. I’ve decided to replace them but at one point I considered putting them back on.
Yep. I found a pic of my original made from cloth asbestos fiber. Also, the replacement version in steel. See below. If there was a way to verify that at least the 3 piece manifold horn would fit the curve of your 75-6 cali version. That would be a start. Then modifying the other bolt hole location.
For sale: sparkomatic vintage aftermarket am/fm stereo radio with cassette and equalizer amplifier. Also 2 Kraco brand speakers—from my 79 fj40.
Here is a description of one I found on eBay. Came with my truck from the original owner.
Comes with all the hardware. See pics Vintage SPARKOMATIC...