Can someone let me know the no of leaf springs being used in a 1.3 jimny at the rear? Are they 3/ 4/ 3+1 jumper or 4+1 jumper? I am using 4 +1 jumper and the ride is very stiff. Using longer shackles.

My SJ-410 ran a 4 pack in the back.

If it's a bit stiff I would look at pulling a shorter leaf and replacing it with a long leaf instead, or just leaving it out.  But if you run hard at all you will end up twisting your rear springs, a traction bar may be required.