So I picked up 92 legacy wagon with automatic high gear doesn't work ,I have a 96 trans from another leg wag will it work in there? Is ther any differences?

Lot of changes between 92-96 , i'm guessing here, but I doubt it could communicate with the ecm.  Others may have done a similar swap and have more info for you.  

1993-1995 4EAT's have the same wiring harness:

http://parts.subaru.com/p/Subaru_1995_LegacyL-Wagon/HARNESS-ASSEMBLY-TRANSMISSION/49234043/24029AA131.html

 

with some wiring, these guys have put 4EAT's into EA vehicles and a guy on subaruxt.com did as well into an XT6:

http://www.ultimatesubaru.org/forum/topic/106406-installing-an-ej-tcu-4eat-into-an-ea-car-4eat/

 

 

is the 92 a speedometer cable, while the 96 has a speed sensor?

Hi,

It'll work, but different FD ratios for 4EATs.

 

'92-'94 Legacy (incl. Turbo) = 3.9; '95-'98 Legacy L/Brighton 4.11; '96-'98 Legacy GT/LSi/OB = 4.44. '99 is Phase II/2 4EAT = stay away.

 

You must match the rear diff. User  your '92 TCM/TCU.

 

'96 speedo cable is electronic, but just swap in the '92...same connector.

 

SEARCH on here to confirm...but I've read more than once that'll work.