Complex sentence: In 1991 the naturally aspirated diesel engine was dropped from the 4x4 program as it didn't have enough power for the 4x4 drivetrain, with most 4x4 LTs being either the 90 bhp 6-cyl petrol or the 102 bhp 6-cyl D24T.
Split into simpler sentences: In 1991 the naturally aspirated diesel engine was dropped from the 4x4 program as it didn't have enough power for the 4x4 drivetrain. So most 4x4 LT's are either the 90 bhp 6-cyl petrol or the 102 bhp 6-cyl D24T.