Sorry chaps , being a beginner at this game, I don't seem to be providing much feedback only asking muppet questions. Anyway, thanks to a kind gent on this site, I solved my alternator space issue by using one off a Hijet Van. It fits lovely but now I've come to wire it in I notice it only has two terminals plus what looks like an earth lug on the body. My Sierra plug has three terminals....which wire gets routed to the lug and which wires fit on which terminals in the alternator ? Can anybody help ?

you should only need 2 wires,the big one goes direct to battery or starter lead terminal,the small one goes to ignition light,it may have a seperate earth wire but check with an ohms meter first or you will fry the alternator

On the Sierra plug, if it is a lucas alternator, you will have two large wires going to big terminals, and one little wire. The two large wires can be joined together and fitted to the bigger of the two terminals on the jap one. No przes for guessing where the little wire goes!
HTH Stu

Thanks gents both

If I join the two wires together though, and the ohther little one goes on the other tag. What's the lug on the Jap alty's body for ? Is that just another earth for suppression or sumfink ?

Without seeing it, difficult to say. Does it seem to be insulated form the metal body? If so, probably an earth. If not, may be a low output terminal used on some alternators to drive a rev counter.
HTH Stu.

Or click here, this might help.....