I was at my local machine shop last week and a guy came in with a box full of what looked like stock connecting rods. At the big end of the connecting rod was an X on both sides of the balance pad. Three of the shop personnel purchased the rods saying they were heavy duty rods. Anybody know anything about these? Are they any better than a stock rod?

nc,
The older "x" rods were supposedly a bit beefier than the stock rods, but since the late 70's the "X" really does not mean a thing. I have seen some of the "flimsy" 305 rods that had the X on them. To be honest with you, for the price that you can get a set of Eagle SIR rods, or the GM powdered metal rods, now days it makes absolutely no sense to even mess with a 30 year old set of stock rods, except maybe for a stock rebuild.