Product Categories

Big Block Swamp Runner Box (35-40hp)


Our 35-40hp kit is perfect for marsh skiffs, bateaus, and big jon boats 14 to 20 feet.

Kit Weight: 75 lbs.

Ships FedEx Ground in Two Parcels – Signature Required

Call to Order

SKU: 40kt60v
SKU: 40kt60v

Product Description

Our Big Block Swamp Runner® Kit includes every part needed to build a longtail motor except for the engine.  Each kit includes:

  • Coupler Assembly
  • Engine Base Mounting Bracket
  • Transom Bracket
  • Heavy Duty 100″ Shaft Assembly
  •  Tiller Handle w/ Squeeze Lever Throttle Assembly
  • Two Aluminum Surface Piercing Propellers, 10″ & 11″
  • Tethered Kill Switch Assembly
  • All Hardware required for assembly


Compatible Engines

Customers sometimes ask us for examples of engines that will fit our Big Block Swamp Runner™ kit.  There are simply too many engine makes and models, to list all engines that will fit.  The following is a shortlist of just a few of the engines that will fit our Large Kits:


1 1/8″ Output Shafts

1 7/16″ Output Shafts

OTHER ENGINE MODELS: Without physically seeing and measuring your engine, we cannot guarantee this kit will fit your application.  If your engine is not listed above, you will need to consult the engine manufacturer, or take some measurements of your engine to ensure it meets the following requirements;

Engine requirements

  • The engine must have a horizontal output shaft. (Vertical shaft engines will not work with this kit.)
  • The output shaft must be a straight (non-tapered & non-threaded) shaft with a keyway.  (Tapered shaft engines will not work with this kit.)

NOTE: Engines with gear reduction are not compatible with this kit.

 Swamp Runner®
by SPS
Beaver Dam
Heavy-duty steel Coupler Housing is zinc plated, then powder coated for superior corrosion protection.
Cast Aluminum
Coupler Housings, Coupler Shafts, and Coupler Sleeve Joints so tough they come with a LIFETIME WARRANTY against cracking or breaking to the original owner.yesnono
Coupler shafts of Small, Medium & Large Kits ride smoothly on high quality Japanese radial bearings. yesnono
Offers longtail shafts featuring premium Bayou Bushings, a low friction proprietary bushing developed by Swamp Runner, and capable of withstanding extreme high temps without melting. Over 1000 hrs in a test tank with negligible wear. This bushing just doesn’t care what you throw at it.yesnono
Longer tiller handle designed to operate while standing up or sitting down, with position holes drilled in the handle, and locking bolts that prevent the handle from twisting in the mounting rings. yesnono
Squeeze type throttle lever that has the full throttle travel of your engine.yesnono
Stainless throttle cable that resists corrosion.yesnono
High quality sealed Japanese bearings in the gimbal mount for smooth, fluent handling of the longtail mud motor.yesnono
Gobs of shaft options to choose from: 5 different longtail shafts lengths varying from a 75" to 120" in length, Along with 4 different shaft options; Standard, Extreme Duty, Saltwater Extreme Duty, and Racing shafts.yesnono
Loads more propeller options than any other mud motor company. With more than 50 different props available including standard props, weedless props, performance props, stainless props, racing props, and even props that come with a .25" bore so you can tap it yourself!yesnono
The Weedless Skeg on Small, Medium and Large kits has a longer entry angle that repels vegetation and slides over logs easier.yesnono
First & only Thai longtail company to offer a Weed Cutter option that can be bolted directly to the weedless skeg using predrilled mounting holes.yesnono
A full time mud motor company offering knowledgeable support from over two decades of experience with Thai longtails in both Thailand and the USA.
Access to an active forum where customers enjoy learning about their longtail, and interacting with other owners and people who KNOW Thai longtails.
Access to numerous parts you can't get anywhere else.

Additional Information

Weight 75 lbs
Engine/Output Shaft Size

, , , , , , , ,

Longtail Shaft Length & Type

B100 Standard Longtail Mud Motor Shaft, B100X Extreme Duty Longtail Mud Motor Shaft, B100XS Extreme Duty Saltwater Longtail Mud Motor Shaft


There are no reviews yet.

Only logged in customers who have purchased this product may leave a review.