My data says
the 1618699 lightweight floating pin 273 rods were also installed in........ 318s up to 1971.
the 2899496 rods were all floating and were installed in all 340s, and in.. 318s from 72 to 73.
the 3418645s were pressed pins and cam in 360s from 71 to 86, and in 318s from 74 to 86 also.
And yes the 496 rods are quite a bit beefier than the 699s; I think the weight difference in them might be up to 100grams. IIRC, my pressed pin 360 rods looked like bushed 340 rods except for the bushings of course. I had lots of bushed teener rods so that is what went into my engine.