K member
The difference is literally a washer (that does nothing) and a couple of half moon washer shapes welded to the LCA pivot tube holes (not the strut rod holes). You could do a better job of reinforcing the LCA pivot tubes with a couple of heavy duty washers from the hardware store welded on with a Harbor Freight MIG welder, even if you don't really know how to weld. Nothing else was different about the K's, and some of the factory welds on that stuff were atrocious.
This is the washer, used to ID the K's
These are the LCA pivot "reinforcements". And the "reinforcement" term is used very loosely.
There are also some original '70 340 cars that didn't have them, so, it wouldn't even really be incorrect to have a '70 340 car without this stuff. Way more info on them here...
340 K Member ??