Kadee 740 Couplers

The 746 is the one with the long shank. I use 740's for plastic cars and 745's on the few brass pieces I have because of the insulated boxes. On a 50-foot car, you should be fine with the 740's.

I found the best looking couplers were not the best operating ones.  Which coupler is best for  your railroad depends on your operating scheme and value preferences.   My operating scheme entails frequent industrial switching and motive power changes.  Due to the depth of the layout (and to avoid shirt sleeve derailments) I wanted hands off coupling and magnetic uncoupling.   During initial operations on my new railroad (4th in O 2 rail) I was not able to achieve  reliable operation with the extreme mix of scale knuckle couplers mounted on my rolling stock.  In the mix were Kadee (7xx & 8xx). Weaver (plastic & metal), Atlas-Roco, AtlasO-China (several versions) and even some old Central Loco Works couplers. My conclusion was to achieve 9x% reliability I had to pick one head design and standardize on it - especially for locomotives, cabin cars, and those cars actively involved in switching moves.  During my tests last year I found:

• For hands off operation Kadee couplers were far more reliable than the other brands (and Kadee offers several draft gear options)
• Kadee 7xx series couplers look quite a bit more prototypical than their 8xx series couplers
• Kadee 7xx and 8xx couplers do not always inter operate well  due to differing head contours and closure spring tension.
• The older 8xx family of Kadee couplers provided more reliable coupling and uncoupling (especially on curves) than the new 7xx design - they have a broader gathering range 
• Tighter inter-coupler tolerances make manual  "pick" uncoupling of 7xx couplers more difficult than with 8xx couplers 

I decided to standardize on Kadee's 8xx family of couplers for optimum hands off operation .

My recommendations: 

• Make you coupler selection early based on your personal preferences and hands on tests
• Install them as you build your roster to minimize a big retrofit project later.    

Would echo the same at Ed and Matt, go with one and stick with it.  

BTW, Nice summary of operating characteristics Ed!

I'm joining Ed in his findings on coupler reliability and decided to stay with the 800 series Kadees.  The 700s look pretty but the 800s work slightly better for operations.  I can heartily recommend the Kadee #241 coupler pick.  It works great and only costs a couple bucks.  I bought two dozen and handed them out as Christmas presents to all my friends.