It seems all gears are the same up to 3rd. 1st gear 3.80 2nd Gear 2.06 3rd gear 1.26 With 1600s having 0.81 at 4th While all 1700/1800/2000 have 0.89. CP and CT codes are from 2L, could you just as well use CM or CN codes from 1.8L?
differentials are different ratios, also the 2 litre 6 rib boxes are physically stronger boxes due to extra ribs/ webs etc
whs^^^ with the diff being higher ratio (4.57) this makes all gears higher overall making it ideal for higher powered engines and motorway driving, the 091 has stronger gears, bearings and a stiffer case again ideal for reliability with higher power engines
