Early BN1 rear axle question

["Alan Seigrist Blue 100" <healey.nut@gmail.com>]

Hi All -

Anyone know off hand what the thread/tap size is for the set screw hole on
the rear bearing hub on a 4 stud BN1 axle?

I thought it was some size of BSF 26 TPI ... but now I'm thinking it might
be BA... can someone please confirm the exact size and TPI?

Thanks,

Alan

'52 A90
'53 BN1
'64 BJ8