I bought a set of used rods out of a LQ4 engine (gen3?) and am rebuilding them in my little shop (aka garage) soon to go into a LQ9 / 6.0 build. There is a 6g variance from lightest to heaviest rod in my set. My plan is to buy another set of factory rods and pick the ones closets in weight for my build as these don't have counterweight section on bottom and top of rod.

I search for cast # 3847 GM Rods. There are tons of them for sale. However, there's a difference in their build. I cannot find any used rods that have the little oil relief on the journal like mine. I'm not sure what this even is about. Additionally, my casting has a Txxx and R on it versus the other rods?

Any ideas?

 

Super helpful thanks!