I belive there where a few operators in Africa that also got the gravel kit.
I believe that the reason why the 737 got gravel kitted was at the time, nobody was interested in certifying a gravel kitted 737-100 which was allready out of production. The -300 and later where not even on the drawing board yet.
When those later generations came around, those CFM engines sit much closer to the ground and have much larger in diameter air inlets, which makes trying to gravel kit one, in my estimation, an impossible task.
OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.