Gearbox numbers Identification

Can some one tell me what the 55 , and 11650 , are they just production numbers ?

May be up for sale , what kind of money are they worth , not seen a CR on up for sale before !!

56 is probably the year of manufacture.
GBN denotes a MK1 OD trans, 11650 is the Serial No. and the CR is a close ratio box which was usually a std fitting in the 2.4 and optional in the 3.4

Numbers within a circle like the 55 are inspector marks; you see a lot of them on cylinder heads.
We put this together about 25 years ago, but it could probably use a little updating as more information has turned up.
http://www.jag-lovers.org/xk-lovers/library/gearbox_reilly/moss_gearbox_identification.html

Thank you , it was on the back of a 3.4 engine , still have that in the garage , sure that is MK2 , so they may be a Factory unit !

But then '56 for a build year woudn’t go …

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I believe the gearbox top is for a MK1, the MK2 top is the same as for the E type. The engine No. of your 3.4 should identify as a MK1 or MK2.

Just done a little research , read Jaguar offered the CR box for the MK1 , as that come out in 55 , the 55 on my box may well be the year !
This one on e-bay has the number 36620 ,and the top is MK2 , just under £3000 asking price I think is a bit optimistic , even if it was in good condition , and no Bell housing !!

Yes. Particularly when it looks like it was dug out from under a tree!