I have been searching heater cores and read a lot on different ones and issues related to some of them. I am providing this more as a helpful guide to what to buy and why cheap is not good and good is not cheap. So if your like me you have struggled and fought to get your heater box out from under the dash. Small children should not be present during this task as it leads to words they probably should not hear and you don't want to have to explain to your wife why your 3 year old is running around saying sum ***** and laughing.. So now its out and you may or may not have ordered a heater core before removal . I purchased 5 total and finally settled on the one I used was the best it was going to be. Pictures are worth a thousand words and I am including a few to show some differences. Now a few of you caught I said I ordered 5, AutoZone just throws them in a box and the bang around and arrive damaged almost every time. My places I ordered were AutoZone x3 and Summit x1 and Classic industries x1. So out of 5 the 3 from AutoZone were wrong and damaged. The one from summit arrived ok but as also wrong for the fitment. The one I ended up using from classic had the proper bends and was the correct size so it fit tight in the heater box. Getting this dam thing back in again make sure the kids are in the house..

 

You sure it fit properly? I also ordered from Classic Industries but had to send the core back because it was 1/2" to thin. Finally ordered from O'Relly's.

 

As you can see in the above pictures the one on the right from Classic and the left was from Autozone. To thin, no curve on the inlet outlet to match on it either. They don't list a part difference for Big block versus small block at Autozone or O'riellys ... So yes I am sure... I did note about a year ago almost everywhere had only the thinner ones. As of about a month ago O'riellys, Autozone, Summit all had thinner ones and wrong bends in tubing. Classic industries which cost about 20.00 more was the only correct fit with proper bends in the tubes..

 

I found the best heater core for my summer car only needs....none!
My heater box dropped and slid out easily, no swearing was necessary. Maybe the 67-68 is packed in there tighter?

 

They are the same.
I take out the glovebox for better viewing/access.
I lay a plastic sheet from under the box to the seat to the top of trans tunnel and out the rocker panel - this way if coolant leaks onto the sheet, clean up is easy.
I don't have to disconnect the cables, but do unplug the resistor block.
I aply new clay weatherstripping for firewall sealant.
I repair the old core - perfect fit.