Good morning johnhenryroff, I use to own 1200 series 657B models, we were on a job in new port beach California back in the 80's the material was surger sand, two 657 hooked together you could not get a load, the first scraper after a 1/4 of a load the back 657 scraper it would start hopping, you could try and get a bigger load and watch the back scraper bounce him self to death or pick up, and the back one would get a 1/4 of a load then the front one would do the samething as the back scraper bounce, between the two maybe one load combined. The solution to that problem was to hook three 657B'b together, the first scraper no problem's at all came out with a good 40 yard load and a fast loading time, same with the second scraper, and the third scraper also 40 yards, three was the answer here. On the older pictures 1960, of the three 657's hooked together I would be willing to bet the three hooked together would out load any three conventional 657, single operator's being pushed, I would think the loading time on the three hooked together would be around one minute flat, maybee even faster, remember they were in good loading material. Remember this was not a high production job. Kewitt wanted volume of yards moved per day, not load count for billing purposes. Your comment on three hooked to gether, I would think that it would of been an honer to of been asked to operate this large three scraper rig. If you had the opertunity to have run the first 657's made they were awfully rough riding scrapers, I had a lot of operating hours on them, I would think operating the three hooked together, you would have a much smoother ride over the scrapers rear tire, and the contractor wouldn't be cracking a whip wanting to know why your not running balls out all day. The three scraper would of been a pleasure to run. Mike Nebergall ( Merry Christmas)