Biggman100, thanks for joining the forums! We value your input and participation...
For openers, the AX15 is used on the 1994 Dodge Dakota, Jeep XJ Cherokee, and the YJ Wrangler. 2.5L four-cylinder and 3.9L V-6 applications of the 1994 Dodge Dakota 4WD pickup truck use the AX15 Aisin transmission. Dodge Dakota 4WD pickups with the V-8 engine use the NV3500 5-speed transmission.
By parts listings, there are differences in complete transmission units from Mopar for each of these models. Six-cylinder Jeep applications use the AX15; four-cylinder gasoline powered Jeep U.S. models use the lighter duty AX5. The AX5 would not fit your Dodge Dakota—nor would it be reliable for that application. Here are the 1994 Jeep parts listings that come up for Aisin Warner AX15 and AX5 transmissions:
COMPLETE 5-SPEED TRANSMISSION ASSEMBLIES FOR JEEP APPLICATIONS
Listings below can be either an AX5 or AX15, depending upon the engine application:
52108022 XJ 2.1 Turbo Diesel Engine 1994
52108121 X1,XJ 2.5 Turbo Diesel Engine. 1995
52108049 YJ,Y1 2.5L Four Cylinder Engine, 4WD
52108045 XJ, X1 2.5L Four Cylinder Engine, 2WD
52108046 X1 2.5L Four Cylinder Engine, 4WD, EGYPT, MALAYSIA
52108046 XJ 2.5L Four Cylinder Engine, 4WD
52108021 X1 2.5L Four Cylinder Engine, 4WD, CHINA, ARGENTINA, VENEZUELA,
52108050 Y1, YJ 4.0L Six Cylinder Engine
52108048 XJ, X1 4.0L Six Cylinder Engine, 2WD
52108047 XJ, X1 4.0L Six Cylinder Engine, 4WD
53009526 ZGZJZ1 4.0L Six Cylinder Engine
52109021 ZGZ1 2.5 Turbo Diesel
1994 DODGE DAKOTA 4WD PICKUPS USE THESE AX15 MOPAR REPLACEMENT TRANSMISSIONS:
52109035 3.9L Engine, 1996
52108465 2.5L Engine, 1996
52108036 3.9L - 6 cyl. Gas
COMPLETE TRANSMISSION NV3500 FIVE SPEED FOR V-8 DODGE DAKOTA PICKUPS
53006633 4x2, Through 11/20/94
52108019 4x2, After 11/20/94
53006634 4x4 1994
52108120 4x4 1995-96
1994 Jeep XJ Cherokee and YJ Wrangler AX15 Adapter/Extension Housing for 4WD
1994 Dodge Dakota AX15 ADAPTER, Transmission 4WD
04636372 Dakota pickup
So, the extension/adapter housing you need can be a Jeep XJ Cherokee AX15 4WD type from an inline 4.0L six-cylinder model! The extension housing differences for the AX15 relate to necessary adapter length, 4WD versus 2WD, motor mount location, clock position of the transfer case and other distinctions.
The complete AX15 transmission listings are also different and may contain ratio differences. If curious, you could research the ratios for a Dodge 3.9L V-6 Dakota versus a Jeep Wrangler or XJ Cherokee application. I have data on the YJ and TJ Wrangler and the XJ Cherokee transmission ratios from 1989 to 2000.
Advance Adapters sells brand new AX15 5-speed transmissions. The Advance Adapters unit is a direct replacement for 1997-2000 Jeep TJ Wrangler AX15 (4.0L inline six-cylinder applications). 2001-up, the Jeep Wrangler 4.0L and the last XJ Cherokee 4.0L 4WD models use the NV3550 transmission, derivative of the NV3500. A very insightful footnote at the Advance Adapters website catalog shares these details:
NOTE: These AX15 transmissions feature a 13 degree tailhousing rotation and are exact replacement transmissions for 1997-2000 Jeep TJ Wranglers. If installing this AX15 into Jeep Cherokee, the tailhousing rotation will be wrong. Cherokee transmissions have a 23 degree rotation tailhousing. The rotation difference will lead to install issues with the Cherokee NP231 transfer case shifter.
This is clearly the distinction on the Mopar extension housings. Measure your transfer case rotation. The Dakota 4WD should follow an XJ Cherokee 4WD tailhousing clock rotation. Presumably, ground clearance and front driveline position/angle dictate the rotations.
Looks like your search for an extension/adapter housing just reached out to the Jeep XJ Cherokee 4WD with a 4.0L inline six. Same part number! I can confirm fit if you find an extension/adapter housing from another model year of the XJ Cherokee 4.0L 4WD AX15 5-speed transmission.
When the bolts snap, there's usually huge elongation or side load force. Sounds like the Dakota 4WD pickup might have had a shock load or suspension bottoming episode from leaping and landing the truck. Does it have a lift kit? Sometimes the driveline angles or length of the drivelines will allow the slip collars and splines to collapse and bottom, exerting severe force on the transfer case, enough to break the case—or possibly snap transmission bolts.