Transmission Swap 4 speed to five speed

[gidis64]

Hey I am new or fairly new to this site just got my 64 D200 long utiline finished in Dec.Hope to get pictures on here soon. My question is can I put a D600 5 speed in to a all original 64 ,4 speed , without many complications .It has a 456 rearend now thought it might help that situation.I have found a 69 or 70 model D600 with a five speed in a local junk yard and wondered if I could have overdrive with this .Do not know any transmission # yet thought I would throw this out to you guys for your thoughts.
Also my 4 speed is very hard to shift ,been all over the adjustment cant seem to make it shift easy, also I switched to synthetic oil that helped a little bit. Are the older (64)transmissions fully synchronized Or would the newer one possibly shift better? I think I might have a extra heavy duty pressure plate but not sure .
Got this truck from my father inlaw , It had been setting in his back yard for twenty years, went back and looked at it one day the old girl was in pretty good shape he had a extended camper on back plus he pulled a toyota behind that. Took it from Missouri to California many times .I have always been a chevy man ,but this old dodge sure has been fun rebuilding. Now I find myself looking for old dodge trucks in peoples back yards or any were.
Thanks Tim

[MowagW200]

Welcome to the community. Look I'm an owner of a '63 to '64 conversion truck based on a W200 with a A 318 and a NP 420 4 speed manual trans behind. In my truck the first (6.88:1) and the second (3.31:1) gear are not synchronized, but the third (1.67:1) and the fourth (1:1) are. Because my truck axles are both 4.88:1 I'm very interrested in the same subject. I don't know if a NV3500 would fit with no mods. For sure a fully synchronized gear box is ways easer to shift than a NP420 (or perhaps a NP435).