[CarolinaHD]

It's doable I just did one, its way easier than trying to convert a pre1987 frame to 4x4.
Helps to have the frames side by side for comparison but here goes for a factory IFS conversion. I did mine on a 2003 3500 cab and chassis Silverado, lb7 duramax and zf6 manual transmission. Converted it to floor shift 4x4, zf6, and a 2006 lbz engine. All the wiring is factory and everything works like it came from the factory that way.

You have to locate, cut out and weld in a sleeve for the upper passenger side frame mount bushing. The lower passenger mount sleeve is already there. Cut out the lower control arm crossmember mount on the drivers side and knock out the tubes the bolts run through. Use the 4x4 crossmember and weld on the new driver side mount. Cut out the driver side upper mount, locate and weld it on the new frame.

I had the engine removed and used a cherry picker to hold the differential in place. Bolted all the mounts to the diff then welded them in place. You'll need a subscription to alldatadiy to figure out the electrical part. Need the transfer case and front diff actuator harnesses. It'll be much easier to use the floor shift transfer case. Just need to relfash the ecm with a 4x4 calibration. Nothing changes in the abs.

You'll be money/time ahead to buy a wrecked truck for all the little parts and wiring or just swap the frame. Cab and chassis frames are harder to find which is why I modified my frame. Wish I had some pictures for ya.