Instrument lamp holder puzzle

[Barney Gaylord <barneymg@MGAguru.com>]

This question is about tach and speedo instruments found in an MGA, 
but which may have come from some other source.  You need pictures 
for this question.  See here: http://mgaguru.com/mgtech/electric/et115.htm

Does anyone recognize the plastic tube and bayonet bulb holder 
arrangement for the indicator lamp?

Barney Gaylord
1958 MGA with an attitude
http://MGAguru.com