Chris you can't do this yourself, also you definetly want to replace the A/C
evaporator at the same time, being a 1992 etc.
We charge $2,200 parts and labor to replace the evaporator, we do these all the
time, I've gotten so good at it I do the 124 dash and heaterbox removal and
re-install the everything with a new evporator in 1 1/2 days, that's not the
actual time I spent on the car off course.
My work comes with the guarranty that you will not notice that the dashboard
has ever been out of the car.
I hate to tell you, there is no other way to get this done.
P.S heater core is in the very same location with the evaporator, no extra
labor when I do the work.