In 1961, the diesel engine was bored out from 2.052l to 2.286l to match the petrol engine. Although the change in diesel option was the only significant change, the Series II was renumbered as IIA.
The first 12-seat station wagon was introduced in 1962. Twelve adults would have been a tight squeeze, but it allowed the vehicle to be classed as a bus and avoid purchase tax. The cheaper price hit sales of the more expensive 10-seat 107” station wagon in the UK market, and the 107” was finally dropped from the product range.
The next major change occurred with the introduction of a 2.625l 6-cylinder petrol engine option on the 109" models in 1967. This engine had been developed for the Rover P4 and P5 cars, but was introduced into the Land Rover range to supply extra power for the anaemic Forward Control S2A. The dashboard is also re-designed in 1967.
Export models had their headlamps moved from the grille area to the wings in 1968. This change was reflected in domestic models a year later.
Another change in 1968 was the introduction of the "1-ton" Land Rover. Externally, this looked identical to the standard Series IIA 109" ( "3/4 ton" ) Land Rover, but was upgraded in a number of areas to handle heavier loads and towing. The most notable upgrade was the use of heavy duty transmission components from the Forward Control models. Overall gear ratios were also lowered to aid with towing.

By the late 1960s, it was clear that changes to the Series IIA were required if Land Rover was going to keep its edge. Hence in 1971, the Series IIA was replaced by the Series III. Cash was limited and market research showed that customers were not looking for radical changes. Hence the Series III was an evolution of the Series IIA design, rather a complete revamp.
The most significant change was the replacement of the gearbox with a completely new gearbox that incorporated synchromesh on all forward gears. The ratios were also revised, with lower Reverse and 1st gears. The Low Range ratio was also reduced. Clutch design was also modified to include a diaphragm spring, resulting in smoother and quieter gear changes. Brakes were also improved, and a heavy duty Salisbury rear axle was fitted as standard to all 6 cylinder vehicles. From 1972, the Salisbury became a standard fitment on all 109" vehicles. The electrical system was also upgraded with the dynamo replaced by an alternator.
The body remained virtually unchanged, although the metal grille was replaced with a plastic grille designed to match the new headlamp position introduced in 1968. Although there were few external changes, the Series III looked very different on the inside. The dash was redesigned with the addition of padding. The instrument panel was moved to be in front of the driver. The door interiors were upholstered, and a much-improved heater was fitted. There were even provisions for a radio!