[Reece]

Those tubes with "MG" suffix mean "metal-glass." They are actually glass tubes inside of a metal shell. Some of the early metal tubes were made that way (by people who weren't RCA) but later that got dropped and metal was metal. As long as the main number matches it doesn't matter if it has MG or no suffix.

Edit: Go cut the grass and let these things sit! They've sat a long time anyway, so what.