Dually to SRW a few quetsions

[77c10diesel]

OK, so I asked about the rear axle on the DWR to SRW swap and know that I will need to swap to a SRW axle to get the width right. What about the rear fenders? If I unbolt the dually fenders, are there just holes to fill in, or would I need a patch panel to replace metal that was cut out?
Also, would I gain any gas mileage? One reason for doing this would be to reduce the overall width, but I would like to pick up a few MPG if possible.
The seller of this truck has another truck for sale also, it is a 3/4 ton long bed standard cab SRW. Can I use the axle from it to swap into the dually?
I am thinking about getting both trucks and making the dually a sinlge and the 3/4 ton into a dually. I would prefer not to swap the whole bed, but will if I need to.
I guess I am looking for input before I go and buy the trucks.

[Blazin]

Sounds like allot of work to end up with the same end result. A dually, and a pickup!
(1) A dually rear end is the same width as the 3/4 ton. Only the cab, and chassis have a narrower rear axle housing.
(2) How do you plan to deal with the bud wheel v/s the single wheel front end?
As far as the bed, swapping a bed is a whole bunch less work than welding up a dually bed, and cutting the quarters out, and mounting the dually fenders on a SRW bed.

[77c10diesel]

The reason for doing this would be to keep the SRW  4 door truck and to sell the regular cab dually. I may end up keeping the 4 door as a dually, but just wanted to know what would be involved because a 4 door truck is big enough as is, to add the wide fenders and 2 more tires just makes it huge and hard to park and fit in my garage. I have a large garage, but it only has a 2 car door on it and so it will fit length wise, but not width because my wife parks on the other side.
As for the front axle I planned to just swap the complete rotor/adapter from truck to truck.