Hi, Way back when I had my '94 sub 6.5 I was on some boards but now I'm a newbie here. I'd appreciate feedback from those that have done their own suburban conversions or upgrades like the ones I'm considering below. Also maybe there is an option I have not considered. Thanks for your feedback.

Experience level: Moderate - I'm good with many repairs/upgrades and have a local friend who is a full time diesel mechanic who is willing to help.

Objective: Revitalize 2003 Suburban (k1500 Z71 5.3) back to reliable work truck and improve fuel mileage while keeping 2003 body

Primary usage: Truck is a work truck for on-site veterinary services; require 4wd use to get to some animals/pasture driving etc.; primarily road usage; minimal to no towing needed.

Philosophy:

1. has 300k+ on all components so upgrade is mandatory,
2. can either spend $ on new or on rebuild
3. Truck is already set up for all equipment, body and interior are in good shape,

(I actually bought a 2013 sub k1500 4wd to replace the '03, but it has significantly less interior room - or maybe it is arranged differently - for my equipment in the back, and I would definitively have to do a suspension lift/upgrade to get it serviceable for getting around non-road environments, also does not have 4low)



Current 2003 Set up:

1. Stock drive train, current Tcase (NP246) has upgraded rub kit/housing
2. Torsion key lift with rear spacers to level
3. Rear air shocks to help support equipment carried
4. 285 M/S tires

Priority list in order:

1. Highly reliable truck
2. have room for all equipment / avoid interior upgrade redo
3. improve fuel economy
4. reduce cost to return to high level of working reliability

Options:

1. Obtain suburban 2500 frame, Donor truck with DMax 6.6 + trans (+ transfer case.. etc.), transfer 2003 sub body
2. Put in Dmax 2.8, 3.0, or other equiv. small diesel + appropriate trans/Tcase in the 2003 1500 frame
3. Replace with another 5.3 + upgrade trans to 6-10sp to improve mileage

I know there are the new Duraburbs, but I'm not sure about the interior space and that's a lot to spend and a super nice truck to use as work truck that gets pretty nasty at times...

I'd also appreciate comments on what each option might require. i.e. option 3 would probably require new computer, etc.



Possible additional upgrades:

1. replace 2003 torsion lift with suspension lift; no plans to use larger tires
2. If stay with 5.3, upgrade air intake and any other that might improve fuel efficiency
3. (crazy idea) wish I could somehow increase the leg room and make it more like a van seating.. I'm tall, enough said.

Thanks again