They could be from any number of manufacturers.
Do they say who made them? MT for sure? I know Cal Custom will have a part # and info on the inside of the cover etc...

Many manufacturers did this for specific markets. Chevy or F... f... (I can't say it) being among the most common.

I bet they would be worth something to the right person. I'd be interested, but then would have to build another motor around them... and then a car around that... so you see my problem (or sickness)

Let us know what you find - Brett - 67 Drop Top 455!