classic motorcycle forum

I have a triumph cub im trying to sell at the moment, its getting quite a few comments because it has a plunger rear end . All the pics ive seen not one is of a cub with this rear?? People have made the comment that this could be a terrier but the numbers are as follows frame=T10348 and Engine=T20 10348 . Here is a link to have a look at the pics of it  http://www.trademe.co.nz/structure/auction_detail.asp?id=37737885    
Any info on this bike would greatly be appreciated Cheers!!