Just fitting merc back axle to Xj and was wondering what the reason for fitting shocks one in front and one behind rear axle is ? 
Can I just mount them in the behind position with no detrimental effects ? Thanks.
GEEK MODE ON:
They are actually aranged that way to help with twisting of the axle and in the event of tire spinning they will help to subdue some of the "tire hop" that may happen. In a properly set up rearend there shouldn't be any horizontal movement seeing as the axle is bolted to a specific spot on the springs. Also it helps to stop some twisting if one side of the axle hits a hole the the other doesn't. if they were both on one side the axel would tilt or "twist" and could possibly damage your universal joints and cause major problems.
To prevent axle hop especially on washboard surfaces. Leaf springs are prone to hop.
If the shocks are mounted on the same side of the axle the springs 'cycle' because of the mass of the axle and the road's impact at the same time at each tire.
There are two solutions:
Increase the shock's damping and the overall ride suffers or
Decrease the damping and install on opposing sides of the axle for a smoother ride.
GEEK MODE OFF:
