I had been in the bourbon when I posted so excuse the tongue in cheek response.
Since it is no longer all original one does not have to battle with one's self about modifying an all original rig. 40 axles are pretty stout and given your thoughts about use, I would wager to say remaining with original axles, or any 40 axle will be your best bet. The main differences you will encounter in the years are 1 - coarse v less fragile fine spline birfields; 2 - drum v disc brakes, and then 3- gear ratio 4.10 [4.11] v 3.88. All these can be addressed seperately using the axle housings you currently have. Or, if you can find much later years, you can swap the entire housing and all the parts installed on them for newer more modern equipment.
Since you are talking about a primarily on road truck, altering perches and putting mega axles or axles from another type of LC on it would probably alter your handling more on road than you would like. Focus on driveability and consider adding front discs with fine splines up front. I prefer Toyota (like from a 60 series or minitruck) rather than the aftermarket discs. You will not be disappointed with that mod. Differential gearing, again, depends on tire size and your use. 3.88 [3.70] will get you a bit better driveability in the highway if you have smaller tires. 4.11s will be needed if you are running 35s and you will be able to move along in the right lane on the interstate without being completely run over. I think you will be happier offroad with 4.11s and the discs and fine spline birfs will also be nice. If you stick with coarse birfields, let us know. Many of us have spares we can donate.
Since it is no longer all original one does not have to battle with one's self about modifying an all original rig. 40 axles are pretty stout and given your thoughts about use, I would wager to say remaining with original axles, or any 40 axle will be your best bet. The main differences you will encounter in the years are 1 - coarse v less fragile fine spline birfields; 2 - drum v disc brakes, and then 3- gear ratio 4.10 [4.11] v 3.88. All these can be addressed seperately using the axle housings you currently have. Or, if you can find much later years, you can swap the entire housing and all the parts installed on them for newer more modern equipment.
Since you are talking about a primarily on road truck, altering perches and putting mega axles or axles from another type of LC on it would probably alter your handling more on road than you would like. Focus on driveability and consider adding front discs with fine splines up front. I prefer Toyota (like from a 60 series or minitruck) rather than the aftermarket discs. You will not be disappointed with that mod. Differential gearing, again, depends on tire size and your use. 3.88 [3.70] will get you a bit better driveability in the highway if you have smaller tires. 4.11s will be needed if you are running 35s and you will be able to move along in the right lane on the interstate without being completely run over. I think you will be happier offroad with 4.11s and the discs and fine spline birfs will also be nice. If you stick with coarse birfields, let us know. Many of us have spares we can donate.
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