The oldest L7 I've worked on was from 1964 or 65, definitely pre 66......although a bit like Triggers broom it was still a serviceable weapon. When I was in BATUS the main stay of L7 variations were H&K Made, did a lot of barrel fitting and serial number stamping then...... Think out out of all the ones that come through the Armourers shop at that time, only Two required some work on the rivets.
If anyone is lucky enough to have a L7 and a MG 42 on the work bench at the same time, have a good look at the bipod and the trigger mech........