2004 Silverado Door Locks / RS

I recetly removed my Avantguard 4 from a '99 Old Body Style Chevrolet.  I already have the DEI 555L that I used to bypass the Passlock system on that truck.

I now have a 2004 Silverado and have read that I can use the 555L to perform the same duties on this truck.  Is this correct?

Also I have read that the 457GW would perform the same function and door locks via the data bus.  Can door locks be installed without the 457GW.

The last time I used a module to lock and unlock their appeared to be a slight delay.  Do not know if it was the alarm or the module.  Mainly do I have to use the 457GW or some equivelant or is their a location to use the standard (-) pulse wires.  Does the 457GW perform other functions that are benificial

Finally is their a better solution than the 457GW?

What a royal pain....

So the GMDL-BP is better?  Because a few quick searches show it to be more expensive than the DEI solution.  I have had great luck with all of my DEI components.  I am just trying to save a buck, but also don't have a bunch of relays laying around like I used to. 

Any other input from people with experiance would be appreciated.  As it stands now I have a module to order.

You can use the MULTI-DL as well if you only want door lock functions while retaining the 555L module. The MULTI-DL is manufactuRED / distributed by Trilogix & is a discontinued model but is now sold cheap if anyone has them in stock