I can get hold of 2 gearboxes ,the guy who sells them says one is a series one box and the other one a xr3i box.How can I be sure? There is a little tag plate on both of them.On the first one is written 85 AB BA FOG 5A 23A and on the other one 89 WT BA FOG 0D 10B .Anyone who can tell me if the guy is right.thanx

 

look though the holes where the driveshafts go, the xr box will have a bar though it,the RS one should not as it has lsd. (this is based on a s2 box knowledge though so may be different for a s1)

 

that is spot on, s1 and s2 boxes do not have bar, all others do i.e xr3, 1600i etc