Hi GTO,
You have raised some very interesting questions.
True GC is the distance between the ground and the lowest part of the vehicle, most often the Differential.
Then the Cheapest Solution is to go for taller tyres.
If the belly/cross member Clearance is considered then, again
1) taller tyres help mildly
2) Suspension Lift helps some more
3) SPOA helps the maximum, but is the most complicated to execute.
If you need more space under the Differential then Taller Tyres 31-10.5-15 is max what the CJ3B can take, to make it more maneuverable you will have to go for MM540 front differential (51" vs 48.5").
The its advisable to Lower you diff-ratio to 4.88:1 or 5.38:1, to compensate for the heavier tyre.
1. Taller tyres : The simplest & cheapest. You can go as long as your stock setup will allow, such that the tyres don't rub against the body / components.
Tried and tested, mechanical mods are bolt on.
2. Alter leaf springs / suspension + larger tyres. Simpler than SPoA, but limited potential (only bend the leaf springs). Also, the ones I've driven have had a very stiff ride (not that stock ride quality was comfortable to begin with!!).
Available in USA costs between 14-60K Leaf spring lift kits. again tried and tested and bolt on.
3. SPoA : A modification that's only getting more popular with Team-BHP's offroaders. Massive tyres permissible. Downsides?
Downsides
1) Steering Angle
2) Differential Pinion Angle & Traction Bars
3) Setup of the Steering Linkages
4) Induced body roll.
5) The leaf spring wears out faster in a SPOA setup.
Ask yourself the WHY of SPOA?
Why do you want to get more room above the tyre is it articulation or to put taller tyres, and get better under the differential clearance, and belly clearance?
4. Suspension Lift kits : Most complicated. New coils, shocks etc. etc. need to be sourced. Not the simplest job to calculate bump stops wheel travel etc. Better for IFS than our setups (?). While new Jeep Wranglers may benefit from ready after-market support, it's not necessarily the case for our Mahindras.
Available for CJ5/CJ7 i.e M&M CJ3B and MM540.
5. Body lift kits : Never been too keen on this. They only lift the body up (and not the suspension). I call this "artificial ground clearance", if done alone, though it may have some value if the body lift is complimenting a suspension lift job.
Not at all recomended, maybe you can go in for the MM540 style body beds, over the CJ series, rubberised-canvas beds, thereby you will get 1/2 to 1 inch height.
My suggestion.
Stage - 1
1) Change Front Axle/Diff-Housing to MM540 i.e 51" track & 4.88:1 diff-ratio
2) Rear Axle to full-Floating with Auto Lockers/LSD i.e 48.5" track 4.88:1 diff-ratio
3) Upgrade tyres to Maxxis Mudzilla 31-10.50-15
4) MM550XD style Skid-Plate under transmission Cross Member.
Stage - 2
1) Upgrade steering system to 1996 Armada type, it bolt on for CJ & MM540s
2) Shock Absorbers - Bilstein 5100 series
3) Steering Damper
4) Front LSD
Stage - 3
NGCS MM550XD and start all over again.
Regards,
Arka