When you say L2A3 and L2A4 in para 3, line 1, thread 5. There was no L2A4*. Or from reading it, do you mean Mk3 and Mk4
(*there was one gun marked L2A4 but that was the first Fazakerley production test-run gun made and it was erroneous)
Sterling did continue to manufacture Mk3/L2A2 butt assemblies as what they called '....needy stock' for nations that requested them but like Tankie says above, anything else could use current Mk4/L2A3 parts. Nigeria (or was it Ghana) returned 500 or so Mk3 guns to Sterling for total refurbishment in the early 80's and it was simpler and economic of course to refurbish them using Mk4 butts. So the trunnion blocks were un-picked, re-positioned and Mk4/L2A3 butts fitted. Problem solved. These guns returned to the UKearly in 2001 as part of a part exchange deal