Advance Adapters AX15 - Manual (Page 36)

3 bolt cover found on
NP205 transfer cases
36
ADAPTER PACKAGES & INDIVIDUAL COMPONENTS ADAPTER PACKAGES & INDIVIDUAL COMPONENTS ADAPTER PACKAGES & INDIVIDUAL COMPONENTS ADAPTER PACKAGES & INDIVIDUAL COMPONENTS ADAPTER PACKAGES & INDIVIDUAL COMPONENTS
for CHEVY TRUCKS for CHEVY TRUCKS for CHEVY TRUCKS for CHEVY TRUCKS for CHEVY TRUCKS
The adapters we manufacture are designed for the GM 4WD NV4500 . We offer complete adapter packages for the most common
transmission swaps. If we do not show a transmission package specifically for your application, more than likely we offer the
individual components to convert your vehicle.
The components in the packages that we do offer can also be
purchased separately. In the applications to follow, we have listed the transmission package(s) plus the individual
components, and any optional or related items that we offer. Also noted are some of the modifications you may be required to
perform.
We currently offer rebuilt NV4500 transmissions. The GM 4WD NV4500 can be purchased under P/N 26-0007R . If you wish to
obtain your own transmission, please refer to the GM identification charts for both current and past OEM part numbers.
GM TRANSFER CASE SUMMARY
The early GMs used a Dana 20 style transfer case and no adapters are available for these vehicles. In 1971, New Process introduced
a model NP203 (chain-driven) and NP205 (gear-driven) transfer case. Both of these transfer cases used various input splines.
As a general rule, all of the transfer cases that couple to a TH350 automatic are normally a 27 spline input; and when coupled to
a manual transmission a 10 spline input; and when coupled to a TH400 a 32 spline input.
The NP203 was used from 1971 to 1979. This transfer case was mated to the TH350, TH400, and SM465 transmission.
The NP205 was used from 1971 to 1991. The 1971-79 NP205 was only found mated to the
TH350 and the SM465 transmission. For 1-ton vehicles between 1979 to 1984/85, GM used
a TH400 and the SM465. The TH400 was equipped with a female 32 spline input, while the
SM465 retained the male 10 spline input. These model transfer cases had a figure-eight front
bolt pattern (shown left). In 1985-91 vehicles, GM started using a different version of the NP205.
The input spline for both the TH400 and the SM465 transmissions was a female 32 spline, and
the front bolt pattern changed to circular bolt pattern.
In 1981, GM introduced the NP208 chain-driven transfer case. The NP208 also has a circular bolt
pattern, and had either a 27 or 32 spline input. In 1988, GM next introduced the NP241 chain-driven transfer case. This transfer
case, as far as bolt pattern and splines are concerned, is identical to the NP208. In 1991/92, GM switched the NP241 from a right
hand front driveshaft to a left hand and went to a independent front axle. The biggest problem with the new front axle was front drive
shaft clearance on the bellhousing. The 32 spline transfer case found in these later model vehicles should bolt directly to the stock
GM NV4500 4WD tailhousing. The length of spline engagement should be checked for proper engagement. The transfer case
shift linkage or stock tailhousing may need some modifications to provide clearance for the transfer case.
GM NEW PROCESS 205 TRANSFER CASE:
The New Process 205 is by far one of the best transfer cases ever built. This cast iron, all-gear driven transfer case is classified
as being reliable and totally bulletproof. This gear box has been used not only in GM production line vehicles, but also Ford and
Dodge production models. The NP205 is sometimes hard to identify. The data plate for this transfer case is located on the upper
front of the case; but in many cases this information has been worn off, and subsequently a NP205 gets confused with a NP203
transfer case. The easiest way to identify the NP205 is by the rear 3 bolt cover on the idler shaft.
Once you know that you have a NP205 transfer case, the next thing is to identify the make (GM, Dodge or Ford). The casting numbers
on these cases are of no help. The Ford transfer case is the easy one to identify
because it is a left hand drop (front driveshaft on the driver’s side). The Dodge and
GM NP205s are a bit more difficult. The cases are identical, both having the figure-
eight bolt pattern. Counting the front input gears are the easiest way to distinguish
between the two. GM transfer cases use either a male 27 spline (TH350), a male
10 spline (SM465), or a female 32 spline (TH400) input gear. The Dodge NP205 was
either a female 23 or 29 spline input gear. The GM female 32 spline shafts were
offered in two stickout lengths: 1979 to 1984/85 had a short stickout, while the 1985-
91 had a long stickout. The 32 spline stickout is important to know when adapting
to a different transmission.