Conair T-48 (DC-6)

Here is a nice video of Conair tanker 48, a DC-6 from 1990. You will see her being loaded with retardant, taking off and then dropping on the Thunder Fire that burned near La Ronge, Saskatchewan (Canada) in June 1990.

I believe but am not certain that you see a Firecat early in the video as well as a CL-215 a little later.