I modified the draft gear box from a Micro Trains Line (MTL) 1025/1029 to work with the RNB87K couplers for several of my HOn3 models, including some Labelle. It would be nice if someone better than me, would make that draft gear box and sell it. I would buy hundreds for my HOn30 fleet.
Also if you’re worried about shorting thru the couplers. How often are you going to couple a rod engine front to front? The rear coupler is almost always insulated anyway, so not an issue. For my brass engines, I have successfully use Sergent RS1P87 & ES1P87 front pilot couplers with very little modifications to the engine.
I "bit the bullet" today and ordered a "starter kit" of RNC87's. I have some LaBelle box cars that have very little space between them when coupled together, so I am hopeful the C's will leave room for the uncupling wand. These cars will belong to the Red Mountain R.R., a switchback line off the summit of my HOn3 Colorado R.R.. I got an email back from Frank @ Sergent last night, and he said I would have no compatibility issues mixing the Sharon's with SBEC87P130K's. I plan to use the sbec's as pilot couplers on my rod engines. All my loco's are DeadRail, so I don't have to worry about electrical shorts if I double head the hill. :-) He also said he can supply the bulk (144) pack of RNC87K's. Said just order the B's, and send an email stating I really want the C's. :-)