Tuff Country 16990 - GM 2001-06 HD 3500 6 kit User Manual
Page 10
 
step # 82. Working on the driver side, secure the new 
rear lateral compression arm mount to the previously 
drilled hole in the stock transfer case cross member. Use 
the new 3/8” x 1 1/2” self threading bolt. Torque to 28 ft 
lbs. Make sure to use thread locker or lock tite. 
Repeat procedure on the passenger side. Special note: 
Make sure that the longer leg of the new lateral 
compression arm is towards the rear of the vehicle. 
Refer to Photo # 20 for proper placement. 
Photo # 20
 
84. Working on the driver side, secure the new lateral 
compression arm to the previously installed rear lateral 
compression arm mount. Secure using the new 1/2” x 3 
1/2” bolt and hardware. Torque the front and rear mount 
to 85 ft lbs. Repeat procedure on the passenger side 
Photo # 21 / Front Location
Photo # 22 / Rear Location
85. Re-install the tires and wheels and carefully lower the 
vehicle to the ground. 
 
86. There is still a couple of steps that need to be 
completed on the front end but these steps will not be 
completed until the rear end installation is completed and 
the weight of the vehicle is on the ground. These steps 
include; the installation of the front sway bar end links 
and the tightening of the new hardware that connects the 
lower control arms to the newly installed sub frame. 
 
Rear end installation:
87. To begin installation, block the front tires of the 
vehicle so that the vehicle is stable and can’t roll forward. 
Safely lift the rear of the vehicle and support the frame 
with a pair of jack stands. Place a jack stand on both the 
driver and passenger side. Next, remove the wheels and 
tires from both sides. 
 
88. Working on the driver side, remove the stock shock 
from the stock upper and lower mounting points and save 
the stock hardware for later re-installation. The stock 
shocks may be discarded. Special note: New longer 
rear shocks are needed, if you have not already 
ordered shocks, please contact Tuff Country or your 
local Tuff Country dealer and order the proper 
shocks. Tuff Country recommends using a 30” fully 
extended nitrogen gas shock. Repeat procedure on the 
passenger side. 
89. Place a pair of hydraulic floor jacks under the rear 
differential and carefully raise up on both hydraulic floor 
jacks at the same time until they come into contact with 
the rear differential. 
 
90. Working on the driver side, remove the stock u-bolts 
from the stock location and discard the stock u-bolts and 
hardware. Set the stock upper and lower u-bolt plates a 
side for later re-installation. Repeat procedure on 
passenger side. 
16985SL. Install the new poly bushings into each end of 
the new front lateral compression arms. Next, install the 
new crush sleeve into the newly installed poly bushings. 
Special note: Make sure to use a lithium or moly base 
grease prior to inserting the new bushings and 
sleeves into the new front lateral compression arms. 
This will increase the life of the bushing as well as 
prevent squeaking. 
 
78. Locate (2) 1/2” x 3 1/2” bolts, (4) 7/16” USS flat 
washers and (2) 1/2” unitorque nuts from hardware bag 
16985NB3. Working on the driver side, secure (1) new 
lateral compression arm to the new front lateral 
compression arm mount on the newly installed one piece 
lower sub frame using the new 1/2” x 3 1/2” bolt and 
hardware. Do not tighten at this point and make sure 
to use thread locker or lock tite. Repeat procedure on 
the passenger side. 
 
79. Working on the driver side, measure from the new 
lateral compression arm mount located on the previously 
installed one piece lower sub frame back to the center of 
the stock transfer case cross member. Special note: 
Chevy has a variation on the placement of the stock 
transfer case cross member. Your measurement 
should either be 31” or 32” long. Remember the 
measurement, this measurement is needed in step # 
80. 
 
80. Locate (2) 1/2” x 3 1/2” bolts, (4) 7/16” USS flat 
washers and (2) 1/2” unitorque nuts from hardware bag 
16985NB3. Also, locate (2) rear lateral compression 
mounts. Working on the driver side, if the measurement 
that you had in step # 79 was 31”, secure the new lateral 
compression arm to the new rear lateral compression 
arm mount rear hole using the new 1/2” x 3 1/2” bolt and 
hardware. Do not tighten at this point. If the 
measurement that you had in step # 75 was 32”, secure 
the new lateral compression arm to the new rear lateral 
compression arm mount front hole using the new 1/2” x 3 
1/2” bolt and hardware. Do not tighten at this point. 
Hold the new lateral compression arm and mount up to 
the stock transfer case cross member and scribe a mark 
on the transfer case cross member where the new mount 
will go. Repeat procedure on the passenger side. 
 
81. Working on the driver side, carefully drill a 5/16” hole 
in the bottom of the stock transfer case cross member. 
Refer to the mark that was scribe in step # 80. Repeat 
procedure on the passenger side. 
 
82. Working on the driver side lateral compression arm, 
remove the new lateral compression arm mount from the 
new lateral compression arm and save the new hardware 
for later re-installation. Repeat procedure on the 
passenger side. 
 
83. Locate (2) 3/8” x 1 1/2” self threading bolts from 
hardware bag 16985NB1. Also, locate the new rear 
lateral compression arm mounts that were removed from