Ok. Here is the information on remote start in your diesel dodge ram.
If your truck was built in 2002 or prior it has a wait to start wire that the remote start system wires into. It sences the negative trigger on this wire while the wait to start light is on. When the light goes out the neggative polarity on this wire will go away (I think it switches to 12volts). And the remote start will see this and then start the truck.
If your truck is a 2003 or newer it is not a simple wire like that. The system is multiplexed meaning it uses different resistances across one wire to control multiple units. So you have to use a pulse timer relay. This is a relay that you can set to send a negative signal to the remote start system for a user set length of time and after that amount of time it will stop applying the negative signal and the remote start will then start your truck.
If you have another question please feel free to shoot me a pm or just reply on this message and I will try to help you out.
I am editing this message because I did not see the bottom half of your question.
I recomend Viper systems. They offer a model 791Xvr. This is a awesome syste. It is the system I will be installing into my truck.
Now there is some other things you have to be aware of as well. Does your truck have sentry key?? (if your key that starts your truck is thick and grey) it has it. This is a chip in the key that when you start the truck a ring that is around the ignition switch reads the chip and allows the vehicle to start. If you have this you will also need a immobilizer interface module.
Now for this the year will matter as well. 02 and down will be DEI's 555c or 555u. The 555u requires a key to be put into a box and hidden under the dash. The 555c learns the code from the key you have.
If your truck is 03 or newer you will need the 555u 555c and a recommended 457c.
The 457c is used to arm/disarm the factory alarm, controls parking lights so you do not have to run wires to under the hood for the connection.
I previously typed that the part did a different task and realized I was thinking of the GM version.
If you have any other questions please feel free to ask.
instead of direct PM keep this going. you might ask a question in PM and then someone else might ask the same question later on. if you keep an open topic that people can search it will make it easier in the future.
besides, I have a 6spd and doing the remote start could cause some problems