Tuff Country 16990 - GM 2001-06 HD 3500 6 kit - Manual (Page 7)

mounting hardware. This will help you make sure that
the bracket is installed properly.
Photo # 11
42. With the help from a buddy, carefully lift the modified
front differential back onto a pair of hydraulic floor jacks
and move the hydraulic floor jacks back underneath the
vehicle so that the newly modified front differential can be
re-installed.
43. Locate (2) 9/16” x 1 3/4” bolts, (4) 1/2” USS flat
washers and (2) 9/16” unitorque nuts from hardware bag
16985NB4. Carefully install the passenger side of the
stock front differential to the previously installed
passenger side differential drop bracket. Secure using
the new 9/16” x 1 3/4” bolts and hardware. Do not
tighten at this point and make sure to use thread
locker or lock tite.
44. Working on the driver side, using a tie down strap or
bungee cord, carefully tie the driver side of the stock front
differential up and out of the way so that the new one
piece lower sub frame can be installed. Once the driver
side of the front differential is tied up and out of the way,
remove the hydraulic floor jacks from under the front
differential.
Photo # 12
45. Locate the new one piece lower sub frame and the
stock lower control arm mounting hardware that was
removed from step # 26. On the driver side, install the
front and rear part of the new one piece lower sub frame
into the stock front and rear lower control arm mounting
points using the stock hardware. Do not tighten at this
point and make sure to use thread locker or lock tite.
Repeat procedure on passenger side.
46. Carefully remove the tie down strap or the bungee
cord that is holding the driver side of the stock front
differential up and out of the way. Let the stock front
differential rest on the newly installed one piece lower
sub frame.
47. Locate the stock hardware that was removed from
step # 28. Install the rear portion of the front differential
into the tab on the rear portion of the new one piece
lower sub frame. Secure using the stock hardware. Do
not tighten at this point and make sure to use thread
locker or lock tite.
Photo # 13
48. Locate the stock hardware that was removed from
step # 35. Secure the newly installed front differential
relocation bracket to the front portion of the new one
piece lower sub frame. Secure using the stock hardware.
Do not tighten at this point and make sure to use
thread locker or lock tite.
Photo # 14
49. Place a hydraulic floor jack under the front portion of
the new one piece lower sub frame. Carefully raise up on
the hydraulic floor jack until the front portion of the sub
frame seats flush with the stock front cross member.
Using the holes in the front portion of the new one piece
lower sub frame as a guide, carefully drill (2) 7/16” holes
into the bottom of the stock front cross member. Special
note: On some vehicles, you may not have to drill the
(2) 7/16” holes, they will already be in the stock front
cross member.
50. Locate (2) 7/16” x 1 1/2” bolts, (4) 3/8” USS flat
washers and (2) 7/16” unitorque nuts from hardware
16985NB2. Secure the front portion of the new one piece
sub frame to the stock front cross member using the new
7/16” x 1 1/2” bolt and hardware. Torque to 42 ft lbs.
Make sure to use thread locker or lock tite. Carefully
remove the hydraulic floor jack from under the front
portion of the newly installed one piece lower sub frame.
51. Working in this order, torque the following stock and
new hardware to proper torque specifications. First, on
the driver side of the vehicle, torque the stock hardware
that connects the rear portion of the stock front
differential into the rear pocket of the new one piece
lower sub frame to 75 ft lbs. Next, working on the driver
side, torque the stock hardware that connects the new
driver side differential relocation bracket to the front tabs
located on the front portion of the new one piece lower
sub frame to 75 ft lbs. Next, working on the passenger
side, torque the stock hardware that connects the new
passenger side differential drop bracket to the stock
location to 75 ft lbs. Next, working on the passenger
side, torque the new hardware that connects the stock
front differential to the new passenger side differential
drop bracket to 85 ft lbs. Next, working on the driver
side, torque the stock hardware that connects the new
one piece lower sub frame to the stock front and rear
lower control arm pockets to 105 ft lbs. Finally, working
on the passenger side, torque the stock hardware that
connects the new one piece lower sub frame to the stock
front and rear lower control arm pockets to 105 ft lbs.
52. Reconnect the 4WD wiring to the front differential.
Also, reconnect any other vent hoses and/or wiring that
was connected to the stock front differential.
53. Locate (2) 6199 poly bump stops from hardware bag
16985PL. Special note: There are (6) poly bump stops
located in the poly bag, (4) are the same size and (2)
are taller, locate (2) of the shorter poly bump stops.
Also, locate (2) 3/8” unitorque nuts and (2) 5/16” USS flat
washers from hardware bag 16985NB1. Working on the
driver side rear portion of the newly installed one piece
lower sub frame, secure the new poly bump stop using
the new 3/8” hardware. Torque to 28 ft lbs. Repeat
procedure on the passenger side. Make sure to use
thread locker or lock tite.