The NV4500, aka eNVy4500, is the ultimate manual transmission
for your Jeep. It is heavy duty, has a low first gear, and it has
an overdrive. It is fairly common and there are adapters available
for it for a wide variety of applications.
The T-18 is probably the most common transmission to swap into a
Jeep because it is heavy duty, relatively inexpensive, and it
can be swapped in easier than almost any other transmission.
The T-19 is basically a T-18 with a synchronized first gear. Most
T-19s are close ratio though, so the transmission is not as popular.
Only some Scout T-19s are wide ratio.
The T-98 is the predecessor to the T-18 and it is as strong as the
T-18, but it is said to have a weaker lubrication system. The T-98
was used in Jeep, Ford, and IH trucks.
The NP435 is almost as popular as the T-18 for the same reasons
the T-18 is popular. The NP435 has a slightly better gear ratio
range, but it hangs a bit lower than the T-18. Some say it is
stronger, some say it is weaker.
The SM465 is a heavy duty, wide ratio, 4 speed transmission used
in Chevy trucks. It is probably the strongest of the heavy duty
four speeds and it is an excellent choice if you are converting to
a Chevy engine.
The SM420 is a heavy duty, wide ratio, 4 speed transmission used
in early Chevy trucks. It has a super low first that is 7.4:1. It is
has a very short overall length which makes it excellent for early
CJs especially with GM engines.
The AX-15 is a good low buck upgrade for people with a Peugeot
BA 10/5 or AX-5 transmission. It doesn't have granny first, but
it is stouter than some other transmissions.
IH 5 Speeds:
Some heavy duty IH trucks and school buses were available with a heavy
duty 5 speed transmission. All of them were 2WD or used divorced
mounted transfer cases and no adapters are available, so these
transmissions are only suitable for larger Jeep trucks. There
is also the problem of fabricating a bell housing.
The Torque Flite 727 3 speed automatic is a good candidate for a
low buck heavy duty automatic for CJs and carbed YJs. The TF 727
was used in full size Jeeps (SJs and J series pickups) in the 80s
and early 90s. It has the standard AMC bolt pattern on the
engine side and it has the circular bolt pattern and 23 spline output
on the transfer case side.
The Turbo 350, aka TH350, automatic transmission is a stout 3
speed automatic transmission. It has been used in various GM
cars and trucks over the years. Because it is a reliable,
common, and short transmission, it is probably the best
automatic transmission to swap in a short Jeep such as a
flat fender or CJ-5.
Saturn/Warn Over Drive
Information on the Saturn Overdrive (originally produced by Warn)
which is a bolt on 0.75:1 overdrive for Jeeps equipped with the
Dana 18 transfer case.
The following pages are being developed to help you find parts
from other makes that can be useful in your Jeep.
Fords are very common, parts are inexpensive, and there is a lot
of Ford parts that are very useful in Jeep vehicles. Many Jeeps
use Ford transmissions, so Ford trucks are a good source of heavy
duty transmissions for Jeeps.
GM cars and trucks are even more common and inexpenive than Ford parts.
Since most Jeeps do not use GM parts though, it is a bit harder to
find uses for GM parts.
Most Jeep and IH trucks use Borg-Warner transmissions. The T-18,
T-98, T-15, and T-90 were all used in both Jeep trucks and IH
trucks. Some parts of these IH transmissions interchange or the
transmissions can be converted relatively easily for use in Jeeps.
Dodge trucks are fairly expensive and harder to find than parts
from other manufactures. Their use is limited in Jeeps.