This ring & pinion set must be used in conjunction with 13-0130 installation kit. Not suitable for ENV or 2HA axles fitted to XK-120 and early MK VII. ENV axles can be easily identified by the lack of a removable rear cover, while 2HA axles have a virtually round rear cover gasket. Because the pinion spline differs from original, this set requires installation kit 13-0130 which includes a new front flange with the appropriate spline pattern. The kit also includes reducer sleeves for the ring gear mounting bolts. Ring & pinion kits are supplied with the early type outer pinion bearing. "Third Type" differentials fitted to later Series II E-Type and all Series III E-Type plus later Jaguars will require outer pinion bearing part number 13-0104 to be purchased separately. The early type bearing has a race outer diameter of 2.875". The later bearing's race is 2.6875" in diameter. Third-type differentials were fitted to Series II cars at 1R.1244/1R.9940 (RHD/LHD OTS); 1R.20335/1R.26576 (RHD/LHD FHC); 1R.35418/1R.42445 (RHD/LHD 2+2) and to all Series III V-12. They are most easily identified by stub axle seal containers that are bolted on to the differential housing. Finally, there were two types of ring gear carriers, one for "short" (larger numerically) gears and one for "tall" (smaller numerically) carriers. When choosing a ring & pinion gear, you must stay within the original ratio range of each carrier. Carrier type "A" (our designation) can accommodate ratios from 5.89 to 3.92; carrier type "B" accommodates ratios 3.73 to 3.07.