First off I just want to say that this forum has given me more insight into my new-old truck. Don't think I'd have been able to fix most of the small things that were faulty with the truck when I got it without the insight of the other users here.

When I bought the truck (85 F250 RWD 6.9 Diesel Extended Cab) the heater core was bypassed. Since I live in Southeast Texas, I didn't figure I'd need heat but realized on a cool humid morning that having no defroster is a pain. I took out the old heater core (truck has A/C, standard output) and went to the autoparts store for a replacement and they came back with an aluminum core that looked like it would fit. Went home and tried to work it into the housing behind the glovebox but it would not fit. The original core had a curved compartment on the top but the replacement had a square compartment which would not fit into the housing. About 1/4" off of the top left corner was in the way (looking from the passenger seat toward the front of the truck).

I went to every autoparts store I could find and all of them had the aluminum square top cores. The online catalogs and in-store catalogs showed the new cores to look identical to the original, but every box had the aluminum cores that would not fit.

I don't want to force the thing in there and damage it, but I do want heat. I'm thinking that maybe if I remove the entire housing assembly I'd be able to get it in there, but I really don't want to go through all that work and have the core still not fit. Some pictures for reference are below.

This is what I want

This is all I can find locally

I've seen some sites that offer the original looking cores (from their pictures) but I'd rather put eyes on it before buying it online and paying more (with the possibility that it will not be the right kind). Help?

 

I never really had a problem when mine failed. I originally put an O'Reilly core in, but it leaked a year later, so I put in a NAPA core, it has been fine for 3 years now. I see that O'Reilly's now has the lower core, but NAPA has the upper core you show. NAPAONLINE®
Both were brass at that time, but it looks like O'Reilly's has gone to the aluminum ones...

 

If you want to run SCA's in your diesel engine, then I would not put an aluminum heater core in it.

 

I went to NAPA but the heater core shown on the website picture part number came back in store as the aluminum heater core. Anybody experience the same problem?

 

I went with a 87 core, they're like the bottom picture. the top one goes in a non a/c truck, you have to remove whole heater box from firewall to install. bottom one is new style, you go through the glove box