i little while back Sperry linked a fuji heavy industry site.  I'm trying to find the 5th gear from a 95 awd 1.8l  transmission   (its a .825)  and to my knowledge it should fit no issues on a 98 RS transmission. 
Trying to setup the car for optimal rally gearing.  tire size will be 196/65/15  and my gearing should end up roughly like  
mph rpm gear calculator 
Its a small change to top speed, but i think it will end up with me being 5-10 seconds faster per stage (on stages that i use 5th gear)  longest straight aways i've seen are tops of 600 yards.       my 1.8L struggles to hit 100 mph ,  even if i double my power i don't think i'll be needing / wanting a top of 140. 
using a .875 5th would be savage, but since its not from an "impreza" its not legal unless the 00-01 Outback shared body style with an impreza.  
 
anyone know how to look up the part number on a gear and where to buy? i'm thinking that site that scott knows , would have it .. ?