Just a note for anyone contemplating heater core replacement on an A2- contrary to the Bentley manual, it is NOT necessary to completely remove the dashboard to pull the heater box and core from the car, at least not on my '92 Golf (Bentley claims the dash must be removed on all Golfs and Jettas post-'88). I did remove the radio and heater control trim plate, the defroster duct and the air distributor duct, and of course the two coolant lines in the engine compartment. It was also necessary to disconnect the air inlet to the heater box from the blower fan, which proved to be a real treat since the two parts are held together with four spring clips, two of which are located next to the firewall and hence aren't visible. The other minor difficulty was the lower stud holding the heater box to the firewall coming loose when I tried to loosen the nut. This was only a minor difficulty, since the stud pulled right out of the plastic heater box. Once everything was disconnected, it was quite easy to wiggle the heater box out from under the dash.
Now it's time to buy some parts and put it all back together...
Garry