I *think* there are more than one versions of the NV5600, first you would have to figure out which one you want to swap in, then go from there. I believe the earlier NV5600's wouldn't take too much to swap in, but I'm not sure about the later model ones.
Dollar for dollar you might want to look at the NV4500 instead of the NV5600. They are cheaper, they are more readily available, and they have the same final drive ratio gear as the 5600. They also have IMO better synchros (brass versus fiber), and if you get the upgraded main shaft with the modified 5th gear improvements it is pretty much a bullet proof tranny. You will need a hyd master slave cylinder, a bell housing, engine adapter, flywheel, clutch, throw out bearing, clutch fork, modified drive shaft, and a few minor things. Pretty much take one out, put the other in. I have found complete setups on ebay for 1500 to 1800, with 1800 including 4x4 setup. The 5600 is about twice the price, and the extra gear is between 3rd and 4th (if I remember correctly). I found this info on a GV website. NV 4500 gear ratio is 1st 5.61, 2nd 3.04, 3rd 1.67, 4th 1.00, and 5th 0.74 and the NV 5600 is 1st 5.63, 2nd 3.38, 3rd 2.04, 4th 1.38, 5th 1.00, and 6th 0.73. The 518 had a 2.45 1st , 1.45 2nd, 1.00 3rd and a 4th OD of 0.69
I dont know about the 1st generation, but a guy here in town had dodge put in a six speed in a 97 12 valve. He also put in a Gear Vendor doubler to make it a 12 speed. He is runnin 85 at about 1500 rpm's according to him anyways. Sorry i cant help more.
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