I had a 91 w/manual (FWD), then a 92 w/auto (also FWD). Now I have a 95
(auto, FWD) and my impression is that the 1st gen Legacies (pre-95) were
more solid cars.
I never had transmission issues with either the 91 or 92. The 91 had a
peculiar habit of locking the doors as you opened the driver door from
the inside (this was documented, I believe)--so you have to stay on your
toes to avoid locking yourself out of the car!
Other than that I had no complaints about my two 1st-gen Legacies.
Unfortunately it was accidents that cut their lifespan short--the 91 at
about 175K and the 92 at 137K. I got my 95 this past December, with
only 64K miles, for $3200; If it proves as reliable as ny other Legacies
then I'll have gotten a great bargain.
With proper maintenance and easy driving, the 1st-gen Legacies should go
over 200K easily. I would look for a car with service records (and a
recent timing belt change, but you probably know that!). Good luck!