Im going to have the IFS Differential and the oil pan off soon for a gasket replacement, was thinking since it would only take an hour at most and i have no clue about the history of the motor that is in my truck, its not rod knocking, making any weird noises and honestly runs like a scalded dog even with the exhaust leak(s), i just want to have a bit of cheap insurance, Would replacing the rod bearings only, no Crank mains, Mess anything up mechanically? by causing binding or other tolerence issues, as far as i can tell, the motor is bone stock and has not been into before. And if its fine to do what should i go with? Tri-metal or aluminum, i want the motor to last as long as physically possible and i plan on turning it low n slow majority of the time Sub <4500 RPM and i want to avoid engine-out work for as long as possible as i lack the means and tools right now.

 

I'm from the school of, "If it ain't broke, don't fix it." While I don't think there should be any problem with doing it, I'm also of the school of not putting "bandaids" here and there when it is convenient. So, with that said, I say leave well enough alone, but it is your vehicle, money and time. Do what makes you happy.

 

Leave it alone if you're not having the crankshaft refinished or at least polished. You will do more harm than good.