The three domestic transmissions most commonly swapped into a Land Cruiser are the SM420 (used in Chev trucks until 1969) SM465 (used in Chev trucks from 1969- 1992) and NV4500 (used in GM and Dodge trucks from 1992-)
|Model||Maker||Offered In||Dates||Speeds||1st||2nd||3rd||4th||5th||Rev||Length||Bellhousing Bore|
|NV4500||New Venture Gear||GM Trucks||92-94||5||6.34S||3.44S||1.71S||1.00S||0.73S||6.34||12||5.125|
|S following a gear ratio indicates it issynchronized|
The SM420 is probably the most popular transmission swap for a LC because of its extremely low first gear. It also has the advantage of being virtually a direct bolt-up to a three Toyota 3 speed bellhousing. All that is required is some minor drilling, a pilot bearing adapter, and a throwout bearing sleave, and an adapter and spud shaft to go between the transmission and transfer case. The biggest disadvantage with the SM420 is parts availability. Because the transmission hasn't been made in almost 30 years, many of the parts have been discontinued. Adapting the transmission to a truck that formerly had a 4 speed transmission is also a bit more involved, requiring either an adapter bellhousing or a modified 3 speed bellhousing to be fitted.
The bolt pattern and bore of the SM465 is different so it will not bolt up to either the 3 speed or 4 speed bellhousing. Although it has a higher first gear ratio, this transmission definitely a better than the swap for those removing a Toyota 4 speed because the parts will be readily available from your local GM dealer. The SM465 is also somewhat beefier than the SM420.
The NV4500 is probably the ultimate domestic transmission. It has both granny low and overdrive in a package that is approximately the same length as an SM420. It is built to handle high horsepower and torque so the internals are very strong. The big drawback for this transmission is that because it is so new, it is very rare in junkyards. It is also extremely popular which drives the price up. The early GM unit is the hardest to find. Probably the ultimate setup is the Early GM/Late GM and Dodge hybrid which gives you the low first gear of the early GM unit combined with the better third gear ratio and synchronized reverse of the Late GM/Dodge transmission.
Of course, all the above mentioned transmission swap will require driveshaft length changes.
If you swap a domestic transmission in along with a domestic engine, matters are simplified. You just have to find the domestic bellhousing that will fit your engine and has the correct bore for your desired transmission.