Hi thank you for your question hope this helps.
I plan to do this same conversion soon to my 01 1500 5.9 gas.
Things you need to know the 04 dodge 1500 with the 5.7 is soled with the manual so it can be done but it is not a cheap swap you are looking around $3,000 in parts that is if you shop around.
Parts you will need
One NV4500 this is the manual transmission i plan to use very strong reliable.
One 5.7 to NV4500 bell housing
One 5.7 flywheel
One clutch and release bearing for a 5.7 engine with manual transmission
One ECU for a '04 5.7 with manual transmission
One transfer case that will bolt to the NV4500
One clutch kit
One slave and master cylinder
Two drive lines front and rear or you can have them shortened
This is a vary helpful site http://www.high-impact.net/transmission_and_gear/oemcomputerconvissues.htmhttp://www.high-impact.net/transmission_and_gear/nv4500.htm#What%20is%20involvedhttp://www.high-impact.net/transmission_and_gear/nv4500.htm#NV4500:%20General%20Information:
You will not need to change the fire wall for clutch mounting.
You will need the clutch / brake
bracket, it is the same size and the mounting holes are in the same place.
As for the computer you will need to get the computer from a 04 dodge 1500 5.7 with the manual transmission you can not "hack the original".
Now the transfer case you need to get the transfer case that will mount to the manual
transmission you plan to get. the one that is in the truck now will not work.
It is vary teddies but if you plan every thing out and have all the parts you should be able to do the swap in a long weekend.
I recommend finding a 04 dodge 1500 with the 5.7 with the manual transmission that was in a wreck that way you have all the parts and you can see how they were be for putting then in your truck. This is what i plat to do.
Hope this helps