sparks,
when a rod "goes" in a inline engine it usually takes out the whole block, crank, cam, etc. rod failures are catastrophic. I want the best rod I can get for the money I've got.

rod failure can be attributed to many causes but there is usually not enough clear evidence left to isolate the real cause.
the best general guess is structural distortion of the big end followed by lubrication failure and then seizing on the throw.
wimpy, poorly designed big ends probably cause more than their share of rod failures.

the stock 292 rod weighs 24oz. the "mystery" rod weighs 28oz all the additional material is on the big end, just where it's needed.

the stock 292 rod is forged of SAE1015 steel. the M rod is made of SAE1145 steel. this results in a better finish and stronger rod.

both rods have 3/8" thru bolts so the bolt pad design will be a more important factor in the fastener strength. again the nod
goes to the M rod.

the use of 283 pistons is of major importance as a balance needs to be struck between skirt length and piston weight; the 1/4" longer rod is a good compromise. forgings exist weighing less than 500gm. the stock 292 scales in at 700 to 800gm.

a friend here is town is starting a new 292. I am going to bend his arms and see if he will use my M rods in his motor. "the proof of the pudding is in the tasting". kalklein