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Mon-Fri: 9AM-5PM Mountain Time.
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for 2015 we'll observe all of the following major US & holidays:

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Novak Conversions
PO Box 3367
Logan, UT 84323-3367
United States
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Novak Conversions
648 West 200 North Suite 1
Logan, UT 84321
United States
(see Return Policies for RMA info)

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Please fill out the following form to email Novak.

Consider the following before mailing:

We wish we were able to answer general technical questions, but the sheer volume of mail we get requires that we focus only on our customers and prospective customers to whom we have a duty.

We focus generally on GM powertrain swaps into Jeeps, and with some expertise in classic Ford swaps into Jeeps, and some limited classic Dodge swaps into Jeeps, and other products as outlined in our Catalog. We are not likely able to help outside of this.

If you are exchanging parts from Jeeps to Jeeps, consider the truism that "the hardest parts to swap into Jeeps are Jeep parts" and that we probably don't have the answer to help.


Take an entertained moment and scan our Mythology vs. Actual Observances article. If one could condense four decades of Jeep conversion sense into one short article, then we think we've done it.

Your Details

It is most helpful to us for you to let us know as many relevant details about your Jeep and project as possible. Tire size and axle ratio (actual or intended, to the best of your knowledge), anticipated use or style of driving (trails? street? rocks? racing? all the above?) can be very useful.

Let us know your name, so we will know to whom we should respond. Your full name and your postal code are helpful if you are requesting components and would like a shipping estimate. Note our emphatic Privacy Policy if you are concerned about spam.

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Existing customers may request that product instructions be sent to them. Please have your invoice number and contact your salesman directly, or contact us through our phone system for express support.

Any other requests for instructions will be passed over.

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Information requests for vehicles other than Jeeps are prioritized on our knowlege of them. Where our focus is so heavily on Jeeps, we will probably not have any helpful information about swaps in other vehicles.


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The Novak Guide to the

Jeep NVG 3550 Transmission

nv3550_transmissionThe New Venture Gear 3550 was released in the Jeep TJ Wrangler and XJ Cherokee in 2000, as the replacement to the AX15 transmission. It is also found in Dodge downsized pickups. It's last year in the Jeep was 2004, after which it was replaced by the NSG370 six-speed.

The 3550 is a takeoff from the New Process 3500 as found in smaller GM truck applications, though all external case features are different.


The 3550 is a top-shifting, longitudinally-loaded transmission. It features five speeds with a direct drive fourth gear and an overdriven fifth gear. It is fully synchronized in all gears, excepting reverse, and has helically cut gears for all speeds.


The NV3550 is 16.7" long and has a cast aluminum case with generous ribbing. With its removable Jeep I6 bellhousing, it measures 23.1". The front bolt pattern is oval shaped and has dowel pins for precision centering alignment to the bellhousing. The front bearing retainer has an integral throwout sleeve for a conventional throwout bearing.

Spline count for the input shaft is 10 splines x 1-1/8" diameter. The output shaft has 23 splines and is flush with the rear face of the transfer case adapter flange.


NV3550 Specs at a Glance:

Make: New Venture Gear
Length: 16.7" 
Weight: 97 lbs.
Case: Cast aluminum
PTO Port: None
Mfg. Torque Rating: 300 ft. lbs. 
Gear Ratios (Jeep): (x-to-1):

4.01 2.33 1.39 1.00 .78 R3.57

Transmission Strength 

The 3550 has a fairly generous torque transmitting capacity (for a transmission of its size) as claimed by it manufacturer. Experience would suggest that it is about the same strength as the AX15, though a small number of failures have been reported to us by our customers. These were probably situations involving extreme terrain or improper use of the overdrive gear.

Popular transmissions to replace the 3550 for higher performance Jeeps include the SM420SM465T18 and NP435 four-speeds.

Transfer Case Compatibility 

The Jeep 3550 was factory married to the NP231 and NP241OR transfer cases. It features the common Jeep / Dodge 6-bolt transfer case mounting face for driver's side drop transfer cases. The 23 spline output shaft makes it compatible with the 23 spline version of the NP231.

Engine Compatibility and Adaptability


Buick V6, Chevrolet Small Block V6 and V8 conversions to the 3550 are done with excellent success.

AMC Jeep 

The 3550 is factory compatible with the Jeep / AMC 4.0L I6 engine. It can also be adapted to 1972-1991 AMC I6 & V8 engines following this procedure.


The 3550 can be cleanly adapted to Windsor Ford V8 and Ford I6 bellhousings that feature the "butterfly" Ford transmission bolt pattern using this Novak kit.


  • New Venture Gear
  • The Novak archives and its customer input
  • Wikipedia
  • DCx Jeep