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The NP205 was a heavy-duty, gear-driven, extremely durable cast-iron transfer case used in Chevy, Ford, International and Dodge full-size trucks. The Chevy versions were erred to as NP205C. They were installed in Blazers, K10s, K20s and K30s from 1966 through 1984.

Bolt Pattern

The Chevy versions of the NP205 transfer case used eight bolts for added strength. The bolts form a racetrack pattern.

Input Specifications

The NP205 was manufactured with four different input splines. From 1966 to 1984, a 10-spline model was available and was most commonly used with the SM465 transmission. From 1971 to 1979, a 27-spline model was available and used with the T350 transmission. The NP205 also came in both a short and long 32-spline format, which was usually attached to a T400 transmission.

Output Specifications

The NP205C was configured with two front output splines. A 10-spline model was manufactured from 1971 until around 1977. A 30-spline model was produced from 1977 until 1984 (in Chevrolets). The 10-spline model came with a 1310-series yoke and the 30-spline model used a flat flange. The transfer case featured a 32-spline, rear output shaft and came equipped with a fixed yoke.

The Ford Explorer was first manufactured in 1991 and is still in production as of 2011. The transfer case conveys power from the transmission to the axles and can be changed from two-wheel drive to four-wheel drive. Problems with this part makes the vehicle virtually unusable. Several issues can be averted with the careful application of preventative maintenance, but when trouble starts you can at least diagnose the most likely reason for the difficulty.

Instructions

1




Drive the vehicle slowly and attempt to engage the four wheel drive through all gears: "2H", "4H", "N", and "4L". Noisiness, jumping out of gear or difficulty shifting indicates further inspection and testing is needed.

2




Place the vehicle on a hard level surface and set the parking brake. Engage the drive through all gears with the Explorer stationary. The shifter should work smoothly through all four settings. Difficulty shifting and noisiness requires investigation of the components. The linkage might be loose, bent or binding in movement. Any of the parts in the transfer case may be worn or damaged. These all indicate further troubleshooting is needed.

3




Jack up the vehicle and place it jack stands. The transfer case is located between the transmission and the rear axle. Check for any leaks or fluid in or around the transfer case, but particularly around the front and rear shafts because they both have seals that can be worn. Locate the transfer case fill plug. It is behind the transfer case damper if installed. If so, remove the damper. Remove the plug and insert your little finger to measure. The lubricant should be at or just below the bottom edge of the plug hole.

4




Remove the transfer case to ensure the components inside are not damaged or misaligned. Where equipped, remove the skid plate. If the damper is still in place, remove it. Drain the lubricant by removing the drain plug on the bottom of the transfer case. Remove the electrical connector, if installed, then remove the speed sensor and speedometer cable from the case. Disconnect both drive shafts. Remove the mounting bracket for the electrical connector, or the vent hose from the shift lever on manual models. For manual models, remove the nut from the shift lever and remove it and the bolts holding the shifter to the extension housing.

5

Place a transmission jack under the transfer case and lift it slightly so that you can use safety chains to attach the case to the jack. Remove the five bolts holding the case, and slide the case down and away from the vehicle. Remove and discard the gasket between the case and the extension housing. Inspect all parts for wear, breakage, misplacement or misalignment. Any parts with those signs must be replaced before reinstalling the transfer case.