penny-wise or pound-foooolish ?
 

While checking out the benz scene at the local pick-a-part, I noticed a '78 w123 that seemed to be fairly descent. Upon further inspection I found that the axle half shafts to be in good shape with the rubber boots suggesting a recent replacement. I own a '84 300sd.
Would the w123 axles fit on my w126? They're awfully tempting at nineteen bucks a pop. What kind of reliability do these axles have? Would it be false economy to replace them with a used part or should I spend three hundred dollars on reconditioned units?

Thanks again!