NV3550 5 Speed Replacing An Automatic in 4.0L Wrangler

NV3550 Conversion

We have had a number of customers who have desired to replace their 3 speed automatic with a 5speed manual. One reason is the 5 speed has overdrive and the 3 speed does not. Another reason is that for whatever reason, they prefer a stick.

The NV 3550 is considered to be the best stick trans ever supplied with a jeep. This package is for 6 cyl jeeps, if you have a 4 cyl automatic, you will need the kit NV3550 replacing a AX5, and we will need to add a flywheel to that kit.

NV4500 Conversion

There is one other popular 5 speed conversion for these Jeeps: The NV4500. This trans is way-oversize for the application, and requires a body lift or extensive floor pan modification to fit. The usual incentive for this conversion is to get the truck style wide ratio, almost granny 1st gear which can be useful for offroad use. On the other hand, this conversion will make a your jeep drive more like a  truck. If this looks like the option or you, High impact does have available a package using the NV4500 replacing the AX15.

NV3550 Conversion Details

Adapting to the Transfer case

NP231 – This is the transfer case found stock in Jeeps from 1989 – 2000, and most jeeps (except Rubicon) from 200-up. Some 87-88 Jeeps will have the 231. Units that came with the 2.5L 4 cyl engine, and units that came behind the Peugeot 5spd (1987-88) will have 21 spline input gears. If you wish to retain this transfer case, you will need to replace the input gear with a 23 spline part (Listed below). The remainder of the NP231 Tcases came with a 23 spline input, and will bolt up directly to a NV3550 transmission

Dana 300 – Note: NV3550 tail is drilled to fit NV231. D300 will fit, however will be rotated Down approximately 9 deg: Tailhousing will need to have 6 holes re-drilled. If desired, a rotation adapter plate kit s available to make this a bolt together.

Atlas II Transfer Case – This case is available in configurations for direct bolt up

Conversion Package

High Impact has available a package providing you with all the primary essential ingredients to this swap. The NV3550 will fit under the stock body without a body lift. Only minor floor pan mods are needed where the shifter handle comes up (you will need to cut a hole and install a boot)


Parts may be purchased separately also.

Package Total$2,523.00
Rebuilt NV3550. One year warranty, unlimited miles. Six months for commercial use. NO CORE CHARGE.
Note: Adapter / Installation kit - This kit supplies a complete new bellhousing and external slave cylinder and hose kit. This system will install easily in a Wrangler. Cherokee will require crossmember and transfer case shifter modification.
Shift Handle (NV3550)
Bellhousing kit incl pilot bearing, release fork & T/O.
Transfer case shifter bracket (NP231)
Throwout bearing
Pressure Plate
Clutch Disc
Master Cylinder
Slave cylinder & Hose kit: When replacing an internal slave, this kit supplies the needed external slave, hose and adapters to the master cyl
23 spl SHORT input gear, NP231