The best of the air cooled cars...other than the late model 993's (1996-98)
are the 1987-1989 Carreras.  They have the updated transmission (with
hydraulic assist), plus the updated interior with better A/C.  All these
years are virtually alike, except for the 1989 Carrera 4...which is actually
the 964 engine and chassis...which was introduced in Europe that year, but
became available in all models in 1990 in the U.S.

The '87's-89's run great...and have the classic body style.  I owned an '88
Cabriolet and loved it, but couldn't use it as an every day car...since it
only had 25,000 orig miles...and I would have destroyed the value in the
car.  But...it drove great!  The Motronic system is far, far superior to the
old CIS in the SC models.

Good luck...hope this helps some.