O Scale Items
Prototype Couplers is proud to introduce its O scale line of scale couplers! These are 100% investment cast in small batches. They sport prototypical features like bottom or top operating detail, three different prototypical manufacturer stampings, and are prototypically scaled. These couplers are highly detailed, reliable, and simple to assemble.
The couplers all come with "compatible shanks", which are designed as direct replacements to the Kadee #740/#745/#804/#805 and will mount perfectly inside a Kadee box. For those who demand the most detail for their model we recommend visiting our friends over at Smoky Mountain Model Works to grab a few highly detailed self-centering gearboxes.
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EC48TK | 4 Easy-to-Assemble AAR Type E Couplers Top Operating Details with compatible shank. For assembly instructions go here. These coupler kits do not include draft gear. Compatible draft gear is available from Smoky Mountain Model Works, Kadee, or further down on this page. | In Stock |
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EC48BK | 4 Easy-to-Assemble AAR Type E Couplers Bottom Operating Details with compatible shank. For assembly instructions go here. These coupler kits do not include draft gear. Compatible draft gear is available from Smoky Mountain Model Works, Kadee, or further down on this page. | In Stock |
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SBEC48K | 4 Easy-to-Assemble Bottom Operating Lower Shelf E Couplers with compatible shank (1968-current). For assembly instructions go here. These coupler kits do not include draft gear. Compatible draft gear is available from Smoky Mountain Model Works, Kadee, or further down on this page. | In Stock |
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SEC48K | 4 Easy-to-Assemble Double Shelf SE Couplers with compatible shank (1975-current). For assembly instructions go here. These coupler kits do not include draft gear. Compatible draft gear is available from Smoky Mountain Model Works, Kadee, or further down on this page. | In Stock |
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FC48K | 4 Easy-to-Assemble Type F Couplers with compatible shank (1954-current)). For assembly instructions go here. These coupler kits do not include draft gear. Compatible draft gear is available from Smoky Mountain Model Works, Kadee, or further down on this page. | In Stock |
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HC48K | 4 Easy-to-Assemble Type H Couplers with compatible shank (1940-current). For assembly instructions go here. These coupler kits do not include draft gear. Compatible draft gear is available from Smoky Mountain Model Works, Kadee, or further down on this page. | In Stock |
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Our couplers do not come pre blackened. This is so we can accommodate customers that may not want to handle parts that have had any chemical treatment. If you would like your couplers chemically blackened before they are sent to you please select the "Blackened" option when ordering.
O Scale Draft Gear Box
We highly recommend picking up some excellent protoypical draft gear boxes from our friends at Smoky Mountain Model Works
Most off-the-shelf commercially available draft gear boxes always seem to be lacking details. Not the DGB48 by Prototype Couplers. This gearbox will fit anywhere a Kadee box will. It sports prototypical details, and the back of the box can be shaved up to 9mm if space is limited. This box is a little narrower than a Kadee which gives it a better scale appearance. The box also will allow for self-centering of our couplers if you use a spring (not provided) between the end of the coupler shank and the knub in the box for holding the spring in place. You may need to shave off some of the model's end sill details and/or relocate the model's coupler screw holes to provide room for the lid's prototypical lip. The lip can be filed off without affecting coupler operation.
DGB48 comes in an unfinished grey 3D resin colour. This is to encourage the consumer to paint the box to promote UV protection.
DGB48 is made to order, additional processing times may apply.
| Part # | Description | Status | Buy Now |
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| DGB48 | 4 - O Scale Compatible Shank Draft Gear Boxes. Replacements for Kadee #817/#818 Draft Gear Boxes. Used in conjunction with our O Scale Couplers for a more prototypical look. Couplers sold separately. | Made to Order |
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Spare Parts
You'll probably want a couple of extra ball and spring packets, too. Even though Prototype Couplers will gladly replace these small parts at no charge if they happen to get lost during assembly, you might want them more quickly than we can send replacements. These are cheap and nice to have on hand.
| Part # | Description | Status | Buy Now |
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| BP48 | Spare Ball Bearing and Spring Pack | In Stock |
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Pricing last revised: August 28th 2025