stock trans is dying, need advice on swap

[torxxx]

Alright my stock 92 trans has lost drive and 3rd gear. I did a transmission service 800 miles ago when it started to slip in drive at random times on the highway. When on a 750 mile drive this weekend and about half way into the trip I lost drive and on the way back I lost 3rd. had to drive the car 75-90 mph in second gear for 250+ miles.

Anyhow I have a 4.11 trans and rear diff out of a 97 legacy wagon and my questions for yall are:

1. Are the legacy axle stubs the same diameter and spline count as the SVX?
2. rear output shaft spline count and size the same legacy and SVX?
3. Which computer will I need to use legacy or svx?
4. Is there anything else I need to know about doing this swap?

Thanks in advance guys