fourwheeler.com FOUR WHEELER OCTOBER 2019 41- All 4 Speed Atlas cases come with the planetary
assembly mounted at the front of the case, fit with
a 2.72:1 and 1:1 ratio. You can opt for either a
4.08, 5.44, 8.16, or 10.34:1 final drive ratio in
the 4 Speed. This number is based on what ratio
is placed in the main body (two-speed unit) of the
transfer case. For us, we opted for a 2.01 in the two-
speed unit, giving us a total of four speeds—1:1, 2:1,
2.72:1, and 5.44:1. This gives us a wide range of
gear reduction, which will be helpful for everything:
sand, mud, and rockcrawling. This also leaves us
gearing options for if we ever decide to put more
power under the hood. - Advance Adapters understands the importance of
details—one in particular being your rig’s speed-
ometer. To ensure it retains a proper readout for our
Chevy’s computer, Advance sent an adapter housing
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2
4
3
that bolts to the back of the 4L60E transmission.
This allowed us to use the provided thread-in sensor
and tone ring, which attaches to the back of the
transmission output shaft.- While the Atlas did come with the proper 27-spline
input, that was about as S-10 specific as it got. To
say that it’s a tight fit under the floor of the cab
might be an understatement. Not wanting to do a
body lift, we used a mix of a grinder, air hammer,
and air saw to manipulate the sheetmetal so the case
could fit under the floor of the truck. - Advance sent us three trick cable shifters, which
help with packaging the case under the truck. We
logged on to the company’s YouTube channel for
adjustment instructions, which saved us time and
headache.