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Message: [QUOTE="me2, post: 320325, member: 3825"] I wrote the original post up about a week ago. Since then I got the new bearing in the bandsaw, the transfer case arrived, the rods arrived, I got my welders (Stick, plasma and TIG) set up and my garage is a lot cleaner. The 12V rods need to go out for new wrist pin bushings. Actually I am not sure they need new bushings, but I am not going to take the chance. New bushings are about $50, but need the work of an engine machine shop to be installed and honed to the correct size. I've been quoted $150 labor for the set of 6, including a steam bath. The engine builder wants a wrist pin from my 6.7 to size the bushings to when he hones them. Which means I need to get my engine torn apart. But I can't do that until I get the engine stand built and I'm presently out of town right now... Why replaced the rods in a brand new 6.7 ? Here are some interesting threads I found on the subject. Montreal guy breaks a rod in his 6.7. - "I towed with it many times and it was a dream good power low egt's fuel efficient it was the perfect set up till well... BOUM!!!" - Stock 6.7 rods, a few mods and some towing. - [url]http://www.cumminsforum.com/forum/6-7l-performance-parts-discussion/448132-blown-rod-help.html[/url] Pictures of Rod Failures - [url]http://www.competitiondiesel.com/forums/showthread.php?t=127171[/url] After 5 Years... it had enough and went boom - 3942579 rods failed. They were polished. - Bad luck or bad polishing ? - [url]http://www.competitiondiesel.com/forums/showthread.php?t=132171[/url] Time for some better rods - Bends 6 STOCK 12V rods in a CR at 900 HP. - None of them break - [url]http://www.competitiondiesel.com/forums/showthread.php?t=125830[/url] Interesting document. [url]www.forging.org/system/files/field_document/FatigueBehavior.pdf[/url] So, from this I deduce... 1) Stock 6.7 rods are not up to the task. If Montreal guy blew them with towing, so will I. 6.7 rods seem to snap, not bend, causing catastrophic damage. If the rods bend before they break, at least you have a chance to catch the problem before it causes damage. 2) The polished and peened 3942579 rods failed. Bad rod or bad polishing ? Rods are heat treated and all it would take is a local overheat with a grinder to wreck them. And they need to be peened to be good if they are polished. Peening too deep actually makes them worse. Do shops that rework rods know this and have sufficient quality control ? 3) Stock 5.9 rods seem to bend but not break. And it takes 900 HP to bend them and even bent they run fine for a long time. Thus I am going to run stock 24V 5.9 rods. And while we are at it, not all 12V connecting rods are the same. Cummins TSB 98T0-5 "ISB Block Parts Compatibility" [ATTACH=full]85126[/ATTACH] My rods are used 3922581 rods with casting number 3922579 from an early 24V engine. I should be more careful when I talk about rods for these engines. In my OP, I stated its getting 12V rods. Technically, that isn't correct. Its actually getting 24V ISB rods. [/QUOTE]