NV4500 repair--difficult?

I have two NY4500 transmissions both with the same problem-- and from what I hear this is a common problem-- the gears grind going into second gear. I have overhauled a SM465 before but know very little about overhauling the NV4500. Are there any special tools or fixtures needed to take the unit apart? The problem is probably the synchro's but some gears could be bad as I just got the trucks and don't know the history. I guess a press will be needed to replace the synchro's? Also anybody know a good place to buy parts? Would it be wise to only go in and replace just the synchro's or should a guy do a complete overhaul? The 1994 truck that i'm working on has 255,000 miles but was told the xmission was replaced 3-4 years ago. Thanks for any help.

Check out Quad 4x4 for parts and a repair manual.