Am starting this discussion to learn the pros and cons of body mounted vs truck mounted couplers. The benefits of each have always been somewhat mysterious to me and would like to get other's experiences on this. There is some mention in various places in the archives, but as far as i know no thread specifically for this. Starting with my own observations: Z scale - using MT rolling stock, body mount is the only way to go. The MT cabooses are truck mounted couplers and they get away with it being on the end of the train and so short. But any other piece of rolling stock was doomed to derailment when backed in reverse over turnouts with truck mounted couplers, but worked fine when the original body mount couplers were used. N scale - most of my rolling stock is MT truck mounted couplers, sometimes i regret it. While they line up better on 9.75" rad curves the sideways force in reverse can make them derail on turnouts when backing long trains. When i run a Kato SD40-2 (with body mount couplers) on 9.75 inch radius curves, the first car coupled to it must also be a body mounted coupler; otherwise the sideways force on the truck derails a truck mounted coupler boxcar even in the forward direction. I have only two cars with body mount, all the rest are truck mount so have not been able to determine the results of all body mount on sharp curves. My tentative conclusion is that body mount is probably the best. But how well does body mount work on 9.75"r curves in N scale or 18"r in HO etc. Is there any other problem (other than re-coupling) with body mount on minimum radius curves caused by the increased sideways swing? Is truck mount better on min radius curves? The only problem i've seen (so far) with body mount is at the bottom of a grade where the trip pin (air hose) of a MT body mount coupler can hit the outside rail on a curve or the frog of a turnout and snag unless adjusted to higher than the recommended height (with the locomotive tilted on the grade bottom with little vertical easement the coupler is angled downwards). Truck mounted couplers remain inside the rails and don't have this problem. In other words, if i was to change all my N scale rolling stock to body mount, would there be any new problems due to 9.75 inch rad curves?