Just got a 92 Legacy Wagon, plan on lifting it 4" , just wondering what it would interchange with once I got the lift done,

Pretty much any EJ powered car up to 2001 or so. Anything before the Legacy ('02?) went to a different rear suspension, and the STi ('05?) went to larger hubs up front.

the legacy rear suspension went to multi-link in 00, and yes, the sti front hubs changed on 05.

 

95-99 Legacy and 02-07 Impreza rear strut tops have a different bolt pattern, but you can use your stock rear tops with 95-99 Outback struts and springs so it all bolts up.

 

The outback has spacers and stuff on the subframes and driveline components, so a 4" lift is not going to work well with your suspension and axle geometry.