Close coupling F units is something that is peculiar to N scale. This thread covers methods and materials necessary to accomplish close coupling for IM F7s. Thanks to several members who offered their techniques. kato also has this issue in some cases, depending on the model. Micro Trains can also benefit from this, but MT eventually issued a close coupling device for their engines. For MT, this draw bar requires that the engines be MUed. Here is a photo by John Sing with the modification accomplished. Additional search terms: F3 FT Kato covered wagon unimate MT F7 F-7 IM