Early axle shafts

Gents,

I have heard talk of the early axle shafts being prone to breakage.  Is the
later EN17 hardened shaft a wise replacement when putting a 1275 in a bugeye?
Is an EN17 simply a stock upgrade on later cars or is it a factory "special"
hardened axle?

TIA,

Larry Daniels
79 MGB LE
72 Midget
58 Bugeye

"You only need two tools: WD-40 and Duct Tape. If it
doesn't move and should, use the WD-40. If it
shouldn't move and does, use the duct tape."