Pressure tested the radiator and two leaks from front and rear fins...SOLUTION?

[CEE1NG_RED]

Any way to fix this without buying a new radiator? Pressurized the radiator to 16#s and the leaks are coming from two locations of the fins, front and rear. Any solutions? JB WELD?? Seems that the previous owner had also fixed some fins using I dont know what solution. I attached a pic of it, where it has some kind of square stamped glue substance on the fin area.

Also, what's the difference with 1, 2, 3, 4 core radiators and how can you tell how many cores you have on the truck? If solution does not work, what radiators out there are still made of aluminum or metal rather than plastic and how many cores? Thanks again...