4 speed to 5 speed swap

[swrpackratt]

  Hi everybody, my name is Eric, I have a '73 3/4ton 4x4 converted to a dually, use it for a work truck, 4 speed is starting to have issues and would like to swap to a 5 speed, found one out of a '88 3/4 ton 4x4, but not sure of the obstacles of swap, I know I'll have to get an adapter for my 205 case, and will need to swap pedal mounts w/ clutch master cylinder, my question is how to tell what trans the '88 has in it, I've read that the np4500 is the one I need but don't know how to I.D. either the '88 or my '73, any help will be greatly appreciated.

[1980c10]

your 73 should have the sm465

[Irish_Alley]

http://forum.73-87chevytrucks.com/smforum/index.php?topic=18325.0

[swrpackratt]

   You are correct, my trans is an SM465 and the '88 has a NV3500 in it so I'll wait until I can find a 4500 and swap at that time. Thanks for your help, here is a link to help ID these tany's if anyone needs it.
Eric




http://www.motivegear.com/tech_info/tranny_guide/tranny_guide.html

[Captkaos]

you would definitely be downgrading by going to the NV3500 from a SM465.

[1980c10]

If you were to get the nv3500 you would want it to be newer than 96(if I remember right) but I wouldn't in a 4x4 plus it has no low 1st gear.
The nv4500 would be great in your application. 
I like my nv3500 in my 2wd 1/2 ton but I would never feel good about towing with it.
A replacement sm465 can be had for next to nothing and rarely have problems if you need an in between trans.
btw what issues are you having with the trans you have now?

[Irish_Alley]

i would do it just for the two extra gears. every one call the 465 a "4" speed i know it is but i only used low for towing when it was up a hill. so to me i dont claim it lol.

[bake74]

     Your right Irish, I only use my low in my 4645 to pull the boat out of the water or when I am towing a real heavy load to start out with.

[swrpackratt]

  The issue I'm having is it will pop out of 2nd gear (or 1st. if you go by the designation on shift knob) when holding back going down a steep incline, I work this truck in an open pit mine quite often and the haul roads are very steep, I need a lower gear than 2nd sometimes to get started, but not as low as the deep under, also would like to add more split in the upper gears for pulling up hill in highway apps. I can run @ 80mph all day until I come to a steep long incline, then have to wait until I get down to about 40-45mph to down shift into 3rd, then I'm stuck @ 45 to the top, very aggrivating , the truck is loaded to the max, I have changed all the suspention componants and upgraded to 1 ton plus, also bagged the rear so it is a very solid ride and the dually conversion helped alot w/ the side to side roll, now I would like to do somthing about the big split between 3rd and 4th ( or 2nd and 3rd, depending on how you want to look at it) the terrian is very mountianous around where I live, and any direction I travel I have to go over a pass, and then down the other side. Thanks for the input and questions, it's nice to have a different outlook to consider..........
Eric