[TR] Mystery differential - MGA prefix

[Randall]

This differential was sold to me as being a Stag unit that had been rebuilt
with 3.45 gears.  But I discovered last night that the new front bearing
does not fit.  While waiting for tech support to open this morning, it
finally dawned on me that perhaps it is not a Stag diff at all ... sure
enough, the number stamped on the housing appears to be "MGA 4906" and even
the rear covers do not interchange (two bolts do not match up, the rest do).

At this point, I think I'm going to try to move the 3.45 gear set into the
old diff housing; but I'm wondering if anyone recognizes the MGA prefix and
what car it's from.  It takes a larger front bearing than the Stag unit
apparently does, which might make it a better unit to rebuild.

The mystery front bearing has an OD of about 2.442", while the replacement
is only 2.250".

Randall