factory bias ply tire questions? L78-15 or 820-15 in 67

[chewychevy67]

I have a 67 and looking to get a reproduction set of original style tires for my ride? my question is when were L78-15 tires first introduced to trucks. I have been looking at factory photos and it looks like 1964ish was when they replaced the older bias ply tires on 1/2 ton trucks. first pic is L78 -15 and last pic is 820 15 ( i know the trucks would have had a smaller size but this is what i think looks good). I believe both are bias ply.