[Russell]

The 5 speeds that are most commonly installed are the NV4500 and the NV3500

The NV4500 is the more expensive transmission. The early Chevy version of the NV4500 have a very low first gear like the SM465 4speeds that were found in the older Chevy trucks, then 3 "normal" gears, and a 5th overdrive gear. The later Chevy and Dodge NV4500s have a higher 1st gear, then the same 3 "normal" gears and a 5th overdrive. These transmissions are very tough, and are found in the early 90's 3/4 and 1 ton trucks.

NV3500 is found in both the C/K 1/2 tons, and the S series trucks. They have 4 "normal" gears, and a 5th overdrive. They are far cheaper than the NV4500 (which typically runs about 1200 - 1500), and far more common to find as well. Only problem is that they are not built tough enough to withstand any real abuse. They will last ok if you drive them nice, but if you like to bang through the gears, and drop the clutch often, you'll want the NV4500.

Of course, there always is the NV5600 (6 speed truck transmission, totally bullet proof) too, and a whole lotta car trannies (T-56 6 speed, etc) that you can install, but they get rather expensive real quick!