Can some one educate me in terms of the difference between the newer style VS spools and the old style ones?

I should clarify: new (external counterweight) and old (internal counterweight).

Reason I am asking is can you use an "old" spool on the "new" reels? I think I had heard that the old ones weren't waterproof (?), but that didn't make any sense - why make a waterproof reel body but not a comparable drag system....lol.

TIA !

AS far as the counterweight, the newer style had the counterweight opposite the line roller on the outside of the flyer while the older style had it inside the flyer on the bottom. The older style drag wasn't waterproof. It has a clip retainer which can be removed so you can gain access to the drag washers if needed. The newer style has a rubber gasket which probably can be done at home( don't know, never tried) but looks a tad more difficult. It also has the drag clicker gear attached to the spool where the older style had it attached to the shaft.This is where the spools are different. The shaft holes on the spool are different sizes as well. This is why you can't change out the spools.

the new ones will not work with the old ones. the old reels have a flattened part on the end of the main shaft to hold the spool. the new ones are rounded and have a pin on the shaft to hold the spool in place.

I also believe the old SS and new style titanium shafts are different diameters.