I just did this job and it took me 12 hours I think, but worth it to have heat. I believe mine was a non-OEM core (It was already purchased and not installed when I bought the truck) and it also did not fit well in the heater box, which by the way to commiserate is a POS to reasseble with all of those bloody flaps flipping around.
I did a little scraping to the inside of the box to no effect, and then resorted to a little bending/banging and filing on the new part until it fit close enough to get the whole thing to at least close within acceptable tollarences for me, and then I used Duct tape to secure the casing and then put together all of the rest of the connectors. I have had no issues and it has been about 3 months now. I did not replace the fan motor, as I probably should have, but gave it a drop of oil at the end joints as instructed in another post. I hope that wasn't foolish, but it works perfectly.
Also of great issue was connecting the heater lines in the engine compartment firewall to the back of the core once installed. I bought new heater lines. Consider connecting them before reinserting into the car and threading them, with assistance, through the firewall. It was almost impossible to access those hoses with only about 1 inch of clearance to the back of the motor.
Good luck. This is good work to do with a friend and refreshments.
I did a little scraping to the inside of the box to no effect, and then resorted to a little bending/banging and filing on the new part until it fit close enough to get the whole thing to at least close within acceptable tollarences for me, and then I used Duct tape to secure the casing and then put together all of the rest of the connectors. I have had no issues and it has been about 3 months now. I did not replace the fan motor, as I probably should have, but gave it a drop of oil at the end joints as instructed in another post. I hope that wasn't foolish, but it works perfectly.
Also of great issue was connecting the heater lines in the engine compartment firewall to the back of the core once installed. I bought new heater lines. Consider connecting them before reinserting into the car and threading them, with assistance, through the firewall. It was almost impossible to access those hoses with only about 1 inch of clearance to the back of the motor.
Good luck. This is good work to do with a friend and refreshments.
