ok so i have a 727...big whoop. but lately ive been looking into getting a 518 i found. but i need some back up info first. is the 518 a three speed with OD or a 4? is it electronic or hydraulically driven OD? will it affect my odometer? will it effect my speedometer? how can i fix my shifter so that i know what gear im in? are the transmissions the same lenth? is it harder or pretty easy to do the swap?......CAN ANYONE ANSWER ALL MY QUESTIONS??!?!?

 

hydraulic without a lockup converter and all the dodge overdrives are 3 speed with overdrive, or a 4 speed, either way ya call it. if i can remember right the trannys are pretty close to the same length, all they are is a 727 with a overdrive unit off the back.

 

What Logan said.
First 3 speeds are hydraulically controlled just like the 727, the 4th/OD gear is controlled by a solenoid in the valvebody which is switched on and off by the PCM in a factory installed application. A simple toggle switch will work for what your doing. You could do pressure switches if you wanted to get fancy.
As long as the cable or sensor hookup is the same, then it shouldn't affect anything with the odometer/speedometer.
Whats wrong with it? Is it in the wrong spot or it doesn't move?
Don't know, not going to run out and measure the 727 under the truck right now, maybe tomorrow.
Should be pretty straight forward, what kind of working conditions do you have?
No, but I will tell you don't skimp on the torque converter if your going to put in a new one. I would also consider a 47RH which would add a lockup converter also, not as easy, requires some new parts and some modifying.

 

so the 518 is just a 727 with a OD unit on the back?

 

my working conditions are really good. all snap on tools and a lift. i was wondering about the shifter because i thought that it was a 4 speed with OD. so that would mean that i would need a 3 on my shifter. but i guess not. and im really confused. is it longer or the same length as a stock cummins 727? and it was rebult 25,000 miles ago, if it comes with the converter will that be okay? cause i really dont have money for a new one. and if the converter isnt can i use my old one off the 727?

 

The 518 is 16" longer than the 727 trans you have now. Also the drive shaft in your truck has a slip joint built into it. The 518 has a slip yoke. The column shift mech will work because there is not a specific position for each gear ( D and OD are the same position) there needs to be a switch on the dash to turn the OD off in certain situations.
Swaping to 518 is not a bolt in and go job. You need ot haev the proper switches and controller to activate the OD. Or you can just put a ON/Off switch on the dash but you need to turn the switch off when OD is not required. Other wise it will always be on ( PITA) Or you could make a controll modual using Relays.
Can be done but not for the faint ant heart(mechanicaly)