If I was going to go to the expense of switching to a D60 front axle anyways, I'd be looking for a 95-99 Suburban 2500.
You can buy them cheap enough now-a-days. They came with 5.7L and 7.4L gas engines as well as a 6.5L diesel engine. You have the big advantage of a much more comfortable, quiet and modern vehicle to drive on a big long trip with all the same interior space as the old suburbans. Most of them are in far better condition than the older 80s / early 90s stuff is and are loaded with creature comforts like AC, heated seats, good heaters, solid sound systems etc.
The Vortec 5.7L engine will fetch you better fuel economy than the earlier TBI 5.7L engines do. The 4l80e is a solid transmission choice which will be found in either generation of Suburban. I have no complaints with the NP243 push button transfer cases but you can find these trucks with an NP241 floor shift transfer case as well if you are solid set against the electric version.
I'd cut the IFS out and install an ORD Solid Axle Swap kit with 47" long springs, a 36" perch width and a mid 80s Ford D60 front axle. You'd be into the swap for 2.5k or so all said and done. I wouldn't lift it more than 3" by using stock 3/4 ton 47" springs from a 73-87(91) truck. I'd also add a set of 4" rear lift springs and some air bags to the back to help keep it level when loaded down with gear. Finish it off with a set of quality 33" tires and some nice Bilstien or King remote resi shocks. I would not run mud tires, they are loud and wear poorly.
You should wind up with a truck that has all the toughness and capability of the old Chevy 1 ton straight axle trucks but topped with all the refinement of the newer rigs. The ride would be better in the new truck with 64" rear springs vs the 52" or 54" rear springs of the older generation of truck.
As far as the diesel engines go, as much as I love those engines they are not a great choice for a road trip like you are describing for a couple reasons.
The first being that there are not a lot of them on the road anymore. That means that parts, even new, can be difficult to track down if you do have problems on the road.
The second being that they are not compatible with ultra low sulfur diesel fuel and require additive. The sulphur used to act as a lubricating agent needed by the injection pump. Without an additive to restore that lubricity the injection pumps fail sooner than later.
The final issue as mentioned above is poor cold starting performance. Once you drop below 5F you pretty much have to plug the block heater in to ensure the truck starts reliably. If you were to run a 6.5L diesel I would suggest that a diesel fired coolant heater such as a Webasto or Espar would be mandatory auxillary equipment.
The 6.5L diesel engines make plenty of power for a light duty engine. They are just as quick as any TBI 5.7L gas engine. They get awesome mileage at 18mpg on the highway but the cost of diesel fuel in the Northern reaches of the continent will shock you. I am paying $5.00 a gallon here right now, and it is more expensive the further North you go. There is also the added expense of the extra maintenance requirements in fuel filters and diesel engine oil as well.
All these extra costs nullify the fuel mileage savings over a gas engine. Dropping a 6.6L LB7 Duramax into one of these newer body style trucks is not difficult and would eliminate a lot of the issues with the 6.5L diesel, but is a very expensive venture costing easily $7 - 10,000 to do it right with a good used engine.
I would tend to agree with the other folks that an Atlas transfer case would be better suited to your rock crawler vs your daily driver / adventure rig. That $2500 would be far better spent on a nice interior sleeping platform with storage space underneith, a roof rack with a cargo bullet for carrying light stuff like bedding / clothing and a awning to provide a dry / shaded place to sit outside of your vehicle. Bumpers with a winch up front, spare tire carrier out back would be a great idea and would also provide room for a second fuel tank to where the spare was to improve your vehicle's range.
You can buy them cheap enough now-a-days. They came with 5.7L and 7.4L gas engines as well as a 6.5L diesel engine. You have the big advantage of a much more comfortable, quiet and modern vehicle to drive on a big long trip with all the same interior space as the old suburbans. Most of them are in far better condition than the older 80s / early 90s stuff is and are loaded with creature comforts like AC, heated seats, good heaters, solid sound systems etc.
The Vortec 5.7L engine will fetch you better fuel economy than the earlier TBI 5.7L engines do. The 4l80e is a solid transmission choice which will be found in either generation of Suburban. I have no complaints with the NP243 push button transfer cases but you can find these trucks with an NP241 floor shift transfer case as well if you are solid set against the electric version.
I'd cut the IFS out and install an ORD Solid Axle Swap kit with 47" long springs, a 36" perch width and a mid 80s Ford D60 front axle. You'd be into the swap for 2.5k or so all said and done. I wouldn't lift it more than 3" by using stock 3/4 ton 47" springs from a 73-87(91) truck. I'd also add a set of 4" rear lift springs and some air bags to the back to help keep it level when loaded down with gear. Finish it off with a set of quality 33" tires and some nice Bilstien or King remote resi shocks. I would not run mud tires, they are loud and wear poorly.
You should wind up with a truck that has all the toughness and capability of the old Chevy 1 ton straight axle trucks but topped with all the refinement of the newer rigs. The ride would be better in the new truck with 64" rear springs vs the 52" or 54" rear springs of the older generation of truck.
As far as the diesel engines go, as much as I love those engines they are not a great choice for a road trip like you are describing for a couple reasons.
The first being that there are not a lot of them on the road anymore. That means that parts, even new, can be difficult to track down if you do have problems on the road.
The second being that they are not compatible with ultra low sulfur diesel fuel and require additive. The sulphur used to act as a lubricating agent needed by the injection pump. Without an additive to restore that lubricity the injection pumps fail sooner than later.
The final issue as mentioned above is poor cold starting performance. Once you drop below 5F you pretty much have to plug the block heater in to ensure the truck starts reliably. If you were to run a 6.5L diesel I would suggest that a diesel fired coolant heater such as a Webasto or Espar would be mandatory auxillary equipment.
The 6.5L diesel engines make plenty of power for a light duty engine. They are just as quick as any TBI 5.7L gas engine. They get awesome mileage at 18mpg on the highway but the cost of diesel fuel in the Northern reaches of the continent will shock you. I am paying $5.00 a gallon here right now, and it is more expensive the further North you go. There is also the added expense of the extra maintenance requirements in fuel filters and diesel engine oil as well.
All these extra costs nullify the fuel mileage savings over a gas engine. Dropping a 6.6L LB7 Duramax into one of these newer body style trucks is not difficult and would eliminate a lot of the issues with the 6.5L diesel, but is a very expensive venture costing easily $7 - 10,000 to do it right with a good used engine.
I would tend to agree with the other folks that an Atlas transfer case would be better suited to your rock crawler vs your daily driver / adventure rig. That $2500 would be far better spent on a nice interior sleeping platform with storage space underneith, a roof rack with a cargo bullet for carrying light stuff like bedding / clothing and a awning to provide a dry / shaded place to sit outside of your vehicle. Bumpers with a winch up front, spare tire carrier out back would be a great idea and would also provide room for a second fuel tank to where the spare was to improve your vehicle's range.
