Open both front doors and remove everything from the firewall to the front seat. No joke.
replace heater core in a 1991 Chevy work truck 1500
YES IT DOES. Yes it does.
copy link and paste... http://www.v6z24.com/howto/heatercore
diagram for a 92 Chevy van g20 Heater core
under the distributor cap
YES The above answer is right. But the problem is that you will have to change the 97 computer,fuel pump, Engine and transmission wireing harness. You will also have to put the 700R4 transmission in that 97 Tahoe. Reason being is that the 91 computer that you HAVE to use won't shift the 4L60E that's in the Tahoe now. Your best bet is to put a VORTEC back in the Tahoe.
Get a manual on your car to do the job right.
You do not need to completely remove the dashboard in order to change the heater core. Remove the water hoses from the heater core. Remove the heater core retaining bolts. Reverse the process to install the new heater core.
In 91 the Tahoe was based on the S-10 so no they will not work. The fullsize SUV was labled a blazer but it was based on the previous platform so no they will not work with the later C/K platform.
I DON'T BELIEVE THERE IS A BLOCK HEATER.
how can i change the turn singal on a 1990 Chevy lumina
Looks like a piece of cake. Check out the following link: http://www.automotiveforums.com/vbulletin/t490722.html Its a how-to with pictures.