HP - when was it used and why?

Over the years, many years, I've heard so many stories about the "HP" stamp on 383's but more so on 440's that nowadays I just roll my eyes around. I know for a fact that the blocks on the 68-70 440's were for all intents and purposes the same and the only time I've come across a 440 that should and did have the HP stamp is one that had the heavier 6 pack rods in it. Hell I'm not even sure if that even makes sense.:read2:

I guess what I'm trying to say is don't get caught in the HP legend.:angry7:, it may not mean a whole hill of beans nowadays.

I wonder if I took my metal stamps and stamped those 2 440's sitting in my garage with "HP" on the pad I could ask an extra $500 for them, see what I mean.
The blocks ARE the same between HP and non-HP....it was the added goodies that got the HP stamp on the block. If you're doing a complete rebuild, you're going to changed those parts anyway.