Damn man, I'm sorry, I got them mixed up again. It is the H bar that is the newer one. There isn't a huge difference between them I guess but none the less the newer one is the one marked "H". I had to look at my own guns again after googling it and sure enough...
That's not the first time I've done that. Brownells has the one marked H in the description as well. Here:
SMITH & WESSON M&P TRIGGER BAR ASSEMBLY, "H" | Brownells