Clive - I've never heard before of a diff that didn't have the date stamped into the top of the central housing - large figures, example 25/3/33 - right from first car to last. If it's a Ruby-type diff it will be a D shaped housing - if a drum type, it would be earlier - either long w/b high chassis with wide track or short wheelbase with narrow track earlier again. If it's a Ruby-type low chassis there should be a zinc plate rivetted to the top of the longitudinal rail, between the engine mounts. Usually near-side but off-side also known. If it has been removed you could find evidence of the rivet holes. If it's the long w/base, high chassis which probability Jon has suggested, the number could be stamped into the top of the long rail about 4" ahead of the front cross-member. If it was in Australia and the chassis number can't be found, the Registration authorities insist that an identification number of some sort be stamped. Perhaps the same in your case? It would help if you let us know what type of chassis it is. Good Luck with your search. Cheers, Bill

Location: Euroa, Australia

many thanks for your reply Jon & Bill
the chassis appears to be a ruby chassis with a 81" wheelbase
and the dif housing is bell shaped but still cannot identify any numbers on it. I will probably take the body off when the weather improves so will be able to get a better look. there is no evidence of rivet holes on top of the frame but there are two holes 4" apart on the side of the o/s chassis member just below the rear engine mount.
many thanks;
Clive

Location: herts

http://a7ca.org/downloads/QuoteThisNumber.pdf
this is useful!

There was also a thread on when the change in the chassis number occured that I posted:
http://pub25.bravenet.com/forum/static/show.php?usernum=2099944454&frmid=5&msgid=1002308&cmd=show

Have a look at the chasis outriggers... nippy type below

https://aus7in.wordpress.com/originality/#jp-carousel-2254