Greetings All,
Can anyone please help me with the identification of serial numbers on BIS gearboxes, were they different from other models in any way??? If so, how can I tell them apart??? Thanks

Ian.

I don't know about serial numbers but I know they were unique to BIS models in that they have a different bell housing (which is very much interchangeable with the air cooled counterparts). I also belive the crown wheel in the diff has a few more teeth but I don't know if the aircooled ones carried them over when the BIS finished.