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Phone Toll Free
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The NP205 gear driven transfer case is considered by
many to be the king of bulletproof. It was supplied in many GM, Ford,
International and Dodge full-size trucks.
GM NP205
Bolt Pattern:
All GM NP205 cases 1971-1985 had a 8 bolt "racetrack" bolt pattern
All GM NP205 Cases 1986-up had a 6 bolt circular bolt pattern
Input Spline: GM Used four different input shaft
configurations on these cases.
10 spline (from SM465 Applications): (1971-85) The most common were units supplied with a 4 speed which typically had a 10 spline male input shaft.
27 spline (from Turbo 350 applications): (1971-79) The units supplied with a T350 automatic have a 27 spline male input shaft.
32 spline SHORT (appx 2" stickout)
32 spl LONG a(appx 3-5/8" stickout)
These are both from (Turbo 400 applications) (also some SM465 86-up may have used a 32 spl input.) We have seen both a short (about 2.0" stickout) and long (3-5/8"" stickout) versions of this gear. The adapter casting in both cases is 4-3/8" long. With the short input, the trans will have an output shaft that sticks out of the main case of the trans appx 4" With the Long input, the trans will have a shorter mainshaft: Sticks out of the main case about 2.5"
Also see data on swapping input gears lower on this page.
1979 to 1985 GM NP205: 8 bolt "racetrack" bolt pattern:
During these years, the GM NP205 showed up behind Turbo 400 and SM465 Transmissions in 1 Ton trucks only.. 1/2 and 3/4 T trucks began to be supplied with the NP208 instead. SM465 units will still typically use the 10 spline input. Turbo 400 units have the stout 32 spline female input (in most cases the short 32 spl input, about 1.5-2.0" stickout) however still uses the 8 bolt "racetrack" bolt pattern.
1986
and Later GM NP205: 6 Bolt circular bolt pattern:
At this point GM updated the unit to use the same 6 bolt circular bolt
pattern used on the NP208, and all subsequent GM full size 4x4 truck
applications. All of them are the 32 spline female input, although
those we have seen are the long (about 3.5" stickout) 32 spl input.
Front Output
GM used two front output shaft configurations, one had a spline count of 10, the other was a 30 spline. 10 splines came before 1977 (roughly) 30 spline shafts came after 1977 (again, roughly). One quick way to tell them apart is by the fact that 10 splines came with a 1310 series yoke output, capable of accepting a CV or yoke driveshaft. 30 spline shafts came with the flat flange on the output, capable of accepting the GM 3R series CV joint.
The 10 spline output will accept the stock 1310; Or a separately purchased 1330 or 1350 Spicer u-joint yoke, and the 1310 CV yoke. The 30 spline flange will accept the 1330 or 1350 CV joints.
Rear Output
The most popular version Is a 32 spline shaft / fixed yoke and will accept a 1310, 1330, or 1350 u-joint yoke, and the 1310 CV yoke.
Some were slip yoke, with a longer tailhousing.
Ford
New Process 205 Transfer Case
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NP205 Ford |
The Ford NP205 transfer case uses the 6 bolt circular bolt pattern . It has a
left hand drop (driver's side). It is supplied with a
31 spline female input.
Rear Output
Is a 32 spline shaft and will accept a 1310, 1330, or 1350 u-joint yoke, and the 1310 CV yoke.
Front Output
Is customarily a 32 spline shaft, same as the rear with interchangeable yokes.
Dodge NP205 Transfer Case
The Dodge NP205 transfer cases are mostly an 8 bolt pattern like the early Chevy. Some late units had the 6 bolt circular pattern. These units all have a right hand drop. Most are supplied with a 23 spline male input shaft and used with a coupler.
29 Spline Dodge: There is a fairly rare 29 spline NP205 used in Dodge trucks behind the Getrag 5 speed. The NP205 used behind automatics are all 23 spline, even in the 1 Ton Cummins apps.
Later applications of this case appear to use a short adapter to bolt to the front of the Tcase, and has the 6 bolt circular pattern found on the transmission tailhousing adapter. This adapter also functions as a bearing retainer in the front of the Tcase and carries the input seal. The casting used for the 23 spline input is different than the one used for the 29 spline, due to the larger bearing and seal. The 23 spline part CAN be machined out to accept the 29 spline parts, but with TLC as it does not leave much meat in some places. These adapters seem to be kinda hard to find on the boneyard circuit, and are apparently no longer available new from Dodge, but they ARE out there.
Cummins NV4500 apps: The 29 spline unit, htat will bolt on the back of an NV4500 DHD, were used 88-93 on Dodge Cummins trucks behind the Getrag 5 speed.
Looks like an NP205, pass side drop, has a housing on the front that goes from an 8 bolt racetrack pattern on the F of the Tcase to a 6 bolt circular pattern on the trans adapter casting. Has a 29 spl male input, with a coupler. The front casting is about 3.5-4" deep
Also see data on swapping input gears lower on this page.
Divorced NP 205 Transfer cases (Dodge – Ford – Chevy)
Are the same as the corresponding married (Married = bolts to directly to the trans), however, divorced units are mounted on their own crossmember separate from the trans. They have a yoke type input, and are coupled to the trans with a short (1-2') driveshaft
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Ford NP205 Divorced |
Transfer Case Specifications:
Low Range reduction ratio: 1.96:1
Transfer Case Overall Length : approx 14”
Front offset distance (Distance from center of input shaft to center of front output shaft) appx 9.75"
(measured from bolt-up surface to U-joint center in Rear yoke)
Swapping input gears in NP205s
Dodge, Ford and GM input gears are all internally interchangeable in all NP205s with one MAJOR detail:
GM 27 and 10sp, and Dodge 23 spl all used a SMALL dia input bearing and seal. These shafts can be swapped directly among themselves.
GM32, Ford 31 and Dodge 29 spl used a LARGER dia bearing. These shafts can be swapped among them selves directly
If you want to upgrade an NP205 with a 10,27 or 23 spl input to a 29, 31 or 32 spl input: The case must be fully disassembled and the opening where the input bearing sits must be machined out to accept the larger dia bearing. A larger seal is also used. The adapter or bearing retainer must fit the Larger dia bearing.
Twin-Stick operation for a 205
The 205 can be twin-sticked much in the same manner as a Dana 300 and other gear drive transfer cases.
There is an internal interlock shuttle pin inside the unit that must be removed:
The transfer case must be disassembled to where the shift rails can be removed. In the front, in the bosses where the shift rails come out, there are detent springs and balls on both shift rails. Also, inside, in between the shift rails, is a shuttle pin that slides back and forth between the shift rails in order to properly sequence shifting for a single stick operation. This shuttle pin will not allow full twin stick operation, and must be removed. You want to keep the detent springs and balls. For full Tcase disassembly info and diagrams, refer to a rebuild manual for the case.
Externally, it is simply a matter of rigging a system that will operate each shift lever independently.
Twin Sticking a 205 when using a Klune underdrive:
The inner shift rail is located inside the front mounting bolt circle: In some cases (such as a Klune underdrive) the housing of the gearbox does not allow a linkage rod to be directly connected to the rail. In this case, it is possible to built a lever system to couple in the twin stick. We did this on a Bronco I had. Unfortunately, I have no pictures of this to publish. I will attempt to describe in words how I made my 205 twin stick work: I made a bracket that botls to the two bolt holes on the outer end of the 205. I ran an lever arm to the inner shift rail which pivots off this bkt. I attached the rod from the inner shifter stick to this lever arm about 1.5" out from the shifter rail.
If you are purchasing a 205 from us, we will perform the internal mods at no additional charge at the time of buildup.
Pictures of NP205 twin stick setup:
