How Do You Identify the NP205 Transfer Case?
There are several different ways of making an NP205 transfer case identification. While the most hassle-free way is to have an online company research your VIN, you can also determine the exact model by visually looking at the transfer case. (One such company that can give you exact specifics on transfer cases for GM, Dodge, and IH trucks is transfercase.parts).
As a general rule, the iron case was a dead giveaway to the NP205 transfer cases. For one thing, the NP205 weighs nearly 140 lbs, while the stock NP208 has an aluminum casing and weighs around half as much.
Many owners get confused with the NP205 and 203, but there are some ways to tell them apart visually. (The NP203 transfer case has four distinct sections bolted together, the front 2 were iron, and the back 2 was aluminum). The makeup of the stock NP208 was all aluminum. (If you pull the transfer cases and see aluminum casing was used as part of the rear output, you can figure it out).
(Please note: This does not include Doubler units that were married versions of the 203 and 205.
The Bolt Pattern
The easiest way to recognize an NP205 is to look for the three-bolt pattern on the rear cover of the idler shaft. This design is unique to the NP205 (NP203 and the 208 have a six-bolt circular pattern). The Dodge and GM 205 units have an identical figure eight-bolt pattern.
The Identification Tag
The id tag is above the front driveshaft output and should provide the model, the manufacture date, and the gear ratio. This information can be challenging to read due to oil, grime, and age, but it can tell a lot. (Look for a metal tag with the “New Process Gear - Syracuse, NY” on it. The tag will have “205” stamped on the silver portion of the model line.
Ford was the only automaker to make the NP205 with a left-hand drop (everyone else used a differential located on the right side (passenger-side front output). So, if the connection to the diff is situated on the left, you are dealing with a Ford NP205.
The Driveshaft Length
The driveshaft lengths are all different lengths, with the 205 being the shortest, about 12 - 13 inches in length with a nut on end). The NP203 has a 22’, and the NP 208 is around 18”). If you measure from the casing to the center of the output shaft, it’s a 205.
NP205 was a gear-driven transfer case, while the NP203 and 208 were chain driven. If your transfer case is making a popping noise when engaged, the chain could be stretched and jumping teeth.
What Trucks Used the NP205?
The NP205 was used in various Ford, GM, Dodge, and International Harvester trucks during the 70s and 80s. While International Harvester used it first in a few applications in the late 60s, Chevy and Dodge were the first of the big three to use the cast-iron transfer case (GM used it until the early 80s). Even after the NP208 replaced it, they continued to use the trusty 205 in their cab and chassis trucks - K30s - from 1981 - ‘91, only with a slip yoke rear output).
Ford used the NP205 transfer case with a left-hand drop in many of its F-Series models from 1973 - 79 (Broncos also had the unit), eventually replacing it with the lightweight aluminum NP208 until 1986, when the company moved to the BW1356 (Borg-Warner). The 205 was divorced until 1977, when Ford finally followed suit and integrated the unit as every other truck manufacturer had. The divorced transfer case made the transfer case sit back farther and required a longer front driveshaft. The result of this configuration was that Ford’s F250 sat considerably higher than other competitor’s fully integrated models - hence the name, Ford “High-Boy”).. Eventually, Ford went with the BW 1356 (Borg-Warner - chain-driven that had an internal oil pump).
Dodge was the last manufacturer to abandon the NP205, but it was also the most sporadic. The company first used the NP205 in its 1969 - 74 models, then dropped it completely in 1975 to go back to the troublesome 203, before finally reversing course in 1980 back to the Np205. The New Process transfer case would remain integral to Dodge drivetrains until 1993. After those years, Dodge used the NP241LHD and NP241DHD for its four-wheel drive applications.
One of the best things about the NP205 is that you cannot kill it. The cast-iron case, along with its beefy internals, weighed a hefty 140 lbs (which was much lighter than the 203 - 195 lbs). Virtually indestructible in off-road settings, it became the love of truck enthusiasts everywhere. This is why so many classic and monster truck enthusiasts loved to tinker with the NP205 because it was as stout a transfer case as you could get, and the fact that they bolted right up to the tranny made them easy to access and work on.
However, as great as it was, the NP205 did have a weakness - the output shaft. Under severe conditions, the shafts (both rear and front) were prone to snapping in two. This weakness created horrible conditions for truck owners, leaving many 4x4 trucks on the side of the road or along a deserted trail, sometimes miles from any help. And in the days before nationwide cell service, truck owners would abandon their trucks to find shelter, safety and eventually a tow truck.
The GM NP205 with its ten-splice output shaft was the weakest of the bunch (Ford and Dodge used 32 spline outputs on the front and rear, which were more stout). Even though GM later developed 30 spline output shafts, it didn’t stop many GM owners from swapping out the stronger Ford 32 spine transmission output shaft. Eventually, aftermarket companies saw an opportunity to provide an upgrade, and today, most classic truck owners make the swap. One such example is the Titan Series 34 Spline kit.
The NP205 came in various sizes of input shaft input depending on the maker and the transmission it backed up. Here’s a list of some of the typical applications and the spline input count for each.
What Is A NP205 Doubler?
Some stock transmission owners experimented with the gearbox section of an NP203 coupled to the complete 205 transfer case yoke units). The marriage between the two transfer cases created a 4:1 super low gear which helped in low-power, high-torque situations. Owners could use the normal 2:1 low gear or shove their transmission into an ultra-low gear. The Doubler will require an adapter to marry the gearbox to the transfer case.
The Doubler was used in various NP 205 applications (particularly GM models). As you might expect, the doubler required a longer overall length (21.5 inches for all versions, measuring from the front face of the 203 to the rear yoke centerline). This made the Doubler the same length as the original 203 and significantly longer than the Ford 203 or 205.