It's probably not so much that those 360 rods are so weak, but that the 390 rods are so much beefier and thus stronger. Compared to other rods that you can use, the OEM 360 rods are weaker. Looks like Survival has several stroker kit options? Talk's cheap as long as you're getting good info. Their tech line might fill in some blanks for you, helping you make decisions whether you buy from them or not.