NV3550 5 Speed Conversion into Wrangler with GM V8

NV3550 Conversion

The NV3550 is an excellent option to consider in smallblock V8 Jeep applications. It will comfortably handle a mild V8 in a vehicle such a as a Jeep, and will fit under the body in a Jeep with very few additional modifications.

NV4500 Conversion

There is one other popular replacement option for the AX15: 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.

NV3550 Conversion Details

Conversion Package

High Impact has available a package providing you with all the primary essential ingredients to this installation. 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.

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


Parts can be purchased separately also.

NV3550 in Jeep w/ GM SB  motor $2,054.25
Also fit s Buick V6
Rebuilt NV3550 Jeep 5 Speed 4WD Transmission. NO CORE CHARGE. Dyno Tested for quality assurance. Included
Shift Tower Included
Shift Handle (NV3550) Included
Adapter / Installation kit – This kit supplies a complete new bellhousing and external slave cylinder and hose kit
Bellhousing and pilot bearing kit (this BH is limited to the smaller 153 tooth GM Flywheel, unless high torque starter listed below is used). Includes release fork, and pivot ball Included
Crossmember adapter plate – CJ & Peugeot 4 bolt (on trans)  to 2 bolt mount adapter $34.40
NOTE: This bellhousing MUST use hydraulic clutch linkage. If you have a mechanical linkage, you will need to “make” the master cylinder fit your firewall and link to your clutch pedal
Slave cylinder $72.28 Included
42″ Stainless Steel Hose Fitting $46.97 Included
Optional: 12″ hose extension $19.21
Optional: 60″ Hydraulic Hose $57.00
TJ applications: Hydraulic Hose adapter (to adapt above hose to stock TJ Wrangler master cyl) incl
YJ applications: Hydraulic Hose adapter (to adapt above hose to stock YJ Wrangler master cyl) incl
CJ Applications: Use “Iron Duke” Master cyl. Hydraulic Hose adapter (to adapt above hose to “Iron Duke” style CJ master cylinder) $19.21
Iron Duke style CJ master cylinder (used in 4 cyl CJs – fits the CJ firewall) $79.75
Master Cylinder $79.75
Adapting to the transfer case: You will need to select the needed adapter components below
NV3550 to Dana 18/20 adapter $401.17
NV3550 to Dana 300: The Dana 300 will bolt up, however the bolt pattern rotation in the NV3550 will likely cause the D300 to hang excessively low. This can be corrected by using a gasket as a template and re-drilling the pattern in the adapter of the NV3550. If preferred a bolt on rotation adapter is available:
Option: Dana 300 Rotation Adapter kit. (3/4″ thick) $200.61
NV3550 to Toyota Gear Drive Minitruck Tcas
NV3550 to NP231 – In most cases a Jeep NP231 case will bolt up directly. The exception: A 231 from behind the 87-88 Peugeot 5sped and a 231 from a 2.5L 4cyl app will have a 21 spline input. This gear will need to be changed to the 23 spl part.
(NP231) Tcase shifter linkage bracket $34.40
NP231 input gear, 23 spline, 1987-94 $190.00 Included
NP231 input gear, 23 spline, 1995-up $190.00
NV3550 to NP207 – The NP207 was used in some Jeeps 1987-88. Most will bolt up directly, however some will have a 21 spl input gear. In this case, the input gear must be replaced with the 23 spl part. $190.00
Clutch components: A stock GM pressure plate may work. The high-top PP in conjunction with the N1714 T/O bearing listed are known to work with the slave cylinder being used. It is also  recommended you replace the clutch components unless they are known to be fresh
Throwout bearing $267.00
Pressure Plate 10.5″ (for 153T FW) $220.00
Clutch Disc 10.5″ (for 153T FW) $110.06
Motor Mounts, Weld in: YJ / GM 350 $3.89
Radiator, Aluminum 1-Core: 1987-05 JEEP TO GM V8 W/ MANUAL WITH LS! OPTION $539.29
Items you may need if you do not have the Correct flywheel for this conversion (The BH supplied in this kit is limited to the smaller 153 tooth GM Flywheel, unless high torque starter listed below is used
153T FW GM Smallblock $250.00
168T FW GM Smallblock (requires High Torque Starter and 11″ Cl as below. Still uses N1714 T/O) $250.00
Pressure Plate 11″ (for 168T FW) $1,800.00
Clutch Disc 11″ (for 168T FW) $110.12
High Torque Starter (Using this starter with NV3550 BH to GM engine will allow use of 168T FW) $235.00
Slave cyl spacer kit – needed to fit high torque starter w 168T FW with this BH. NC