Quote Originally Posted by satan18 View Post
Hear is my theory for what it is worth,now the standard ib had the ally screw cap on the end which was removable.

The exploding tail version had a two peice cup and gaine which replaced that ally screw plug.

I suspect although these are Z marked,they were never armed up as tail bangers and hense the screw cap stayed in place.

Although that could be changed if i manage to get the right parts for the ends

Nice example i cannot see the gain pot in the picture, is it steel or bakerlite like the SD1, SD2 gain pots. Dave