[mickmate]

If they have two tags one would read BPL (British Power Lock) the other is ratio as previously said. If it is a Jag rear it is likely Salisbury which use bigger crown wheel bolts I think. The Dana gear sets will fit but you have to open the bolt holes up to match it to the carrier. That also gives a much wider range of ratios to choose from. I have some good tech articles on the Jag rears send me a PM or something with your e-mail and I'll send you a bunch of info on them.