Of the two basic adaptor designs, I may consider the Anderson type design......but, would “never” consider the old style, which essentially is a piece of pipe extending from the fifth wheel pin down to the ball in the truck bed.
The pipe type extension, acts as a lever, tremendously “multiplying” the torque the the trailer frame. If you study the differences in material strength, and geometry between a gooseneck type trailer and a fifth wheel trailer design......it should be obvious why you should not use the “pipe-type” adaptor! memtb