Loosen the bolts on either end of the dash that hold the dash in place (one fairly large bolt on each side). That combined with a flexible attachment, and you should be able to get to the top screws on the housing from under the dash. Remove the clamps from the hoses that attach to the core, have a catch pan as you will spill anti-freeze everywhere. Do this when the engine/vehicle is cold. Remove the passenger seat prior to working on this and you'll be much happier. If you have the ability, taking the door off would also get you some additional room (which is needed when you are my size -- 6'3 and
270lbs). This is one of the most frustrating jobs on this vehicle. Very poor design, obviously the designer never had to replace a heater core on one of the prior to their production....especially not at 10F in December in a driveway in South Dakota :-) Buy the best heater core, not a remanufactured one, as you DO NOT want to have to do this again any time soon. This is an all afternoon project that will have you cussin' by the time you are done, but is not difficult in terms of mechanical skill. Guaranteed to test your patience though. I have no idea what shops where you live charge to do this. Call them or stop by and ask them. My guess is $200-$400 range.Also, if you google this group with the key words heater core S-10 you'll find volumes of information.
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and click on the groups option. Make Google your friend.
Big Chris
Big Chris