NV3550 5 Speed Conversion into a CJ With GM V8 & Dana 300

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 5 speed option for the Jeep CJ: 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

Jeep Dana 18 and Dana 20

Most Dana 18 or Dana 20 transfer cases can be bolted to the NV3550 through the use of a standard adapter (listed below in the kit detail)

The notable exceptions are:

1969 – 1971 Jeeps with the T14 transmission used a 10 spline shaft. In this case, it is necessary to replace the original 10 spline input gear with the equivalent gear-tooth-count 6 spline version.

The 70’s Jeeps with Turbo 400 automatics had a 32 spline output shaft and used a spud shaft in an adapter housing. The T-case input gear is carried on the spud shaft. This gear is not compatible with the six spline version: You must replace this input gear with the equivalent gear-tooth-count 6 spline version.

Scout versions used with an automatic transmission: This gear will have a 23 spline configuration. It must be replaced with the Scout gear from the manual trans applications, which will have the correct 6 spline configuration.

Dana 300 – The Dana 300 was the standard transfer case supplied in CJ jeeps 1980-up. Note that the NV3550 tail is drilled to fit NV231. D300 will fit, however will be rotated down approximately 9 deg: To correct this, the NV3550 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, and is a definite upgrade option over stock units.


Parts can be purchased separately also.

NV3550 in Jeep w/ GM SB motor Pkg Pricing Total
1 Rebuilt NV3550. Includes shift tower. NO CORE CHARGE. Included
Shift Handle: You will need to modify your existing shifter by cutting off the current end, and welding on a steel plate and drilling holes thru the steel plate to bolt up to the stub sticking out of the trans.
Adapter / Installation kit – This kit supplies a complete new bellhousing and external slave cylinder and hose kit
1 Bellhousing and pilot bearing kit (this BH is limited to the smaller 153 tooth GM Flywheel, unless high torque starter listed below is used) Included
1 Slave cylinder Included
1 Hydraulic Hose (to adapt new slave cyl to stock YJ Wrangler master cyl) Included
1 Hydraulic Hose adapter (to adapt new slave cyl to “Iron Duke” style CJ master cylinder) Included
Adapting to the Jeep Dana 300 transfer case
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) $172.65
Clutch components: A stock GM pressure plate and Throwout bearing 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
1 Throwout bearing $34.31
1 Pressure Plate $167.89
1 Clutch Disc $145.00
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 $242.50
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


NV3550 in Jeep w/ GM SB motor Pkg Pricing Total