What are these lifters out of?

Hello all, please see the pictures, are these Chrysler Solids? Someone told me they might be Slant 6 ones, but i found 16 of them from a purchase years ago, so i am wondering if they also used these in the 273 mechanical cam engines? If so, were they good lifters or did they have a weak spot in the narrow area? I want to use them in a solid cam 360 because they have just been refaced perfect. THanks.!

solid lifter.jpg

solid lifterr.jpg