Couplers, couplers, couplers

[chuck]

This sounds like HO.  These are probably horn hook couplers and you are talking about replacing them with Kadee's?  Depending on the cars/trucks, these may be simple swap outs.  The cars may need more work if these are truck mounted couplers and there are no "pockets" for the Kadee's to mount to.  BTW, this is primarily Lionel/American Flyer/Standard Gauge forum.  The Model Railroader section caters to HO/N.

[cnw1995]

Hi gczerny, welcome to this forum. It sounds from your description that these cars are smaller than the O gauge ones usually discussed here. Maybe HO scale? I suggest reposting this on the Model Railroader forum.

[Anonymous]

I was out of the hobby for quite a while, and now that I am getting back into it, I have a dilemma.  I have some 25+ year old rail cars that I'd like to have run with my new locos that I have purchased.  The problems is the old cars have the old couplers, and I'd like to update them.  I just don't know what brand couplers I need, or should I look for replacement trucks with the new couplers already installed.  It seems to me the pin size that holds the coupler in place varies from each brand of car (ex.: Tyco, Bachman, dicast cars, etc.).  Can someone please give me some insight on this?

Thanks,