I tore down an 88 truck engine, and the rods were marked with an X on the caps. Other than that they looked like ordinary OEM rods.
Are those what is referred to as X rods?
In what way are they different than regular rods? If at all?

 

Yes those are "X" rods. They are considered better but i'm not sure why, probably different metallurgy. Also there could be better bolts in them i don't know.

 

I've noticed that the shops that sell them ask about $40 more for them than similarly equipped, recon'd OEM rods.
And they're "limited availability" too

Maybe they're better cause they come from a TBI truck, therefore they couldn't possibly have seen any serious abuse.
I know these haven't, I could floor it in park and it wouldn't rev over 5k

Oh well... I guess I'll put some ARPs in em and use em

 

They are worth more because people will pay more for them.

The rod is not the weak link, it is the bolts.

 

Okay... So I decided this calls for a careful lookin' over.
I did a side by side comparison along with some quick measurements. And the X rods are thicker in the side sections of the I beam area, by maybe about .035 per side.
They're also a bit heavier.
My scale isn't that accurate so I'm guessing that it's 5-10g.

Add to that the fact that they're out of a motor that's never been raced and that means they're a good set of rods once there's a set of ARP bolts in there.

Now we know what X rods are