Small block heads with no casting numbers

I recently picked up this 360 It has some odd heads they don't have any casting numbers. They have the time stamp markings and some random numbers but no casting numbers. One has 15h and the other is 12 h I believe buts that's all the numbers I see. They appear to be smog heads they have the smog ports under the exhaust ports. Im thinking maybe a factory warranty head or something?

20210316_183848.jpg

20210316_183829.jpg

20210316_183811.jpg

20210316_183804.jpg

20210316_183715.jpg

20210316_183733.jpg

20210316_183737.jpg

20210316_183749.jpg

20210316_183752.jpg

20210316_183759.jpg