After building a new coupler carrier for the rear of a B Unit, (after Atlas coupler broke - common with Atlas short couplers that were never updated to their newer design) I discovered that the Kadee 806 short couplers can be easily mounted into the short Atlas coupler box. This is how:
1. File the flange off the underside of the Kadee 806 coupler so that the bottom is smooth at the thinner level.
2. Remove the Atlas O coupler carrier from Loco.
3. Remove the coupler cover and coupler from the carrier.
4. Cut the Atlas centering spring by about 1/3 in length.
5. Install the thinned Kadee 806 into the Atlas box with the spring between the post and the rear of the coupler.
6. Install Atlas cover and check that coupler centers then reinstall on Locomotive.
7. You will now have reliable coupling and uncoupling with fewer broken couplers.