spectra premium heater core issue ? / anyone recommend a good heater core ?

There is ONE sentence that tells everything that needs to be said.

"then i connected the old used one to the heater hoses ( which is brass and i am guessing copper or steel ? ) and the tubes were to hot to hold almost instantly , and the center / rows parts got too hot to touch within a minute or 3 ."

If people can't get what the problem is with that said, then, well...
The metal used makes near zero difference, and I would laugh my *** off if someone told me they could tell if a heater had an aluminum or other metal core by the temp it puts out.
Obviously that heater core blows.
Doesn't mean all Spectra heater cores blow, but that one does.