The final drive ratio is stamped on the front of the differential housing near the top bolts.
10/43 = 4.300:1 for 1500 and 1600 cars
10/41 = 4.100:1 for 1600-MK-II
 9/41 = 4.556:1 commonly used with close ratio gearbox for competition.
11/43 = 3.909:1 optional and rare when new, but now more common as a modification.
Other ratios were available on special order or may be obtained from other model cars.


Someone had to ask, what is the significance of the "S" or "T" above the ratio numbers? Well, I'm not sure yet, but the 10/43 is original from an MGA 1500 with 10-spline halfshafts. MGA 1600 standard issue was 26-splines early and 25 splines later. MGA 1600-MK-II was 25 splines. The 11/43 in this picture is originally from an early MGB (1962-1968) with 25-spline halfshafts. The S or T may designate the type of splines for the halfshafts (maybe), but don't have a definitive list.