Advance Adapters 50-9801 - Manual (Page 2)

GM TRUCK 4SP MODEL SM465 10 SPLINE
TO JEEP NP 21 SPLINE T/C
ADVANCE ADAPTERS INC. P/N: 50-9801
P.O. Box 247, 4320 Aerotech Center Way Old Part No: 711098-21
Paso Robles, CA 93447 PAGE 2 OF 3
Telephone: (800) 350-2223 Fax: (805) 238-4201 Page Rev. Date: 01-28-00
SPECIAL NOTE: The components packaged in this kit have been assembled and machined for specific type of conversions. Modifications to any of the components will
void any possible warranty or return privileges. If you do not fully understand modifications or changes that will be required to complete your conversion, we strongly recommend
that you contact our sales department for more information. This instruction sheet is only to be used for the assembly of Advance Adapter components. We recommend that a
service manual pertaining to your vehicle be obtained for specific torque values, wiring diagrams and other related equipment. These manuals are normally available at automotive
dealerships and parts stores.
GM & CHEVY SM465 4 SPEEDS 1968 & UP:
This transmission can be identified by a case length of 12". The casting numbers on the case should be GM465452, 6273212
or 3901127. The top shift cover casting number should be GM3901131. The P.T.O. opening is available on both sides
of the main case. This transmission has a non-synchro first gear. The gear ratios for this transmission are as follows:
First Gear ...................... 6.56
Second Gear .................. 3.58
Third Gear ..................... 1.70
Fourth Gear .................. Direct
Reverse .......................... 6.09
In order to use this transmission with our kits, you must make sure that you have the proper output shaft from the original
4 speed transmission to couple to the new Advance adapter. Currently, we manufacture the adapters for both 35 spline
and 10 spline output shafts. This Kit uses a 4WD 10 spline output shaft. Make sure that the spud shaft and the main shaft
do not bottom out causing interference and eventual bearing failure. If your transmission has a 32 spline output shaft, then
you will be required to change to the other designs listed. The correct transmission can be found in all two wheel drive
vehicles 1968 & up, and all four wheel drive vehicles 1968-80. The transmissions which are not compatible are 1981 &
up four wheel drive K1, K2. The four wheel drive K3 models are equipped with a 10 spline output shaft that can be used
with our kits. The part numbers for the new shaft, if required, are as follows:
GM Part No. 6259663 - Output shaft with 10 splines
GM Part No. 3932265 - Output shaft with 35 splines
The shaft has a rear bearing that is retained with either a snap ring or special lock nut. Without this snap ring or lock nut
in the proper position, the shaft will walk forward into the input shaft causing severe damage. Make sure that the shaft is
locked by either the lock nut or snap ring to avoid severe damage.
The new spud shaft that we have furnished with your kit must slip over the output shaft without bottoming out or causing
spline interference. With the spud shaft in position and the adapter on the new transmission, you must be able to rotate the
shaft freely. There are certain applications that may require a slight grinding of the original output shaft to prevent the original
shaft from bottoming out inside the new coupler. The special coupler has the ability to float between the 4 speed output
shaft and the 21 spline input gear. Make sure that the limits will not permit a disengagement of either of the splines.
The adapter plate that we have furnished for your new transmission has a special pocket that has been machined into the
transmission side for clearance over the reverse counter shaft. Make sure that the counter shaft in the transmission is rotated
for proper engagement into the new adapter housing.
The right side of the main case will need to be ground off for clearance of the front output yoke on certain installations.
We recommend a trial fit with your transfer case and front output yoke so that any modifications that may be required can
be done before final installation. This is a good time to set up the shifter linkage for the transfer case controls.
Make sure that the adapter fits flush against the back of the transmission and indexes properly over the two bearings. You
must use the gasket provided between the adapter housing and transfer case. This will prevent oil from exiting between
the two.