I have a huge backlog of coupler fitting to attend to, mainly because to get things running I tend to fit Kadees to end vehicles and leave the tension lock couplings in place within rakes. Some of these temporary measures are over two years old now, suprising given that I hate tension locks with a vengeance - time certainly flies.
So, freshly laden with guilt, couplers and a height gauge, I've taken some small steps towards resolving the situation, starting with my fleet of JGA hoppers. One of Bachmann's least botched arrangements, the NEM socket is actually at the correct height, but due to sloppy tolerances the installed couplers can droop under load - the trip pins can thus catch on pointwork and cause derailments.
An easy one to put right, for a change. Lever the coupler pocket out with a small screwdriver and replace it upside-down to gain a little height. Then fit your chosen Kadee coupler with a shim of 10 thou plastikard underneath it to remove any slop in the pocket. I find this gives me an exact match against the Kadee height gauge seen in the photo.
I'm using Kadee #18 medium-length couplers here and they give a nice close-coupled effect as can be seen in the photo - the two vehicles are pulled as far apart as they'll go. When propelled the vehicles will negotiate a crossover made from Peco large radius points without buffer locking and also just about get round my 30 inch radius curves. If you've got tighter radii then try the slightly longer #19 couplers.