Claymore is correct. Fluid filled is an optional model.
I think the side port ones (14) and first stages (14/21/22) with 3x 3/8 LP and 1x 7/16 HP are worth more. As was pointed out above good condition will add to the price. I've picked up older second stages for $20-30 and older firsts for similar. I have a complete project set, earlier models, no side port and all 3/8 ports but do have a new 3/8>7/16 hp port adapter, two seconds and a first, for sale with rechromed face plates, new service kits, new decals, new exhaust Ts etc, will include second stage tools (bent screw driver and wrench). If anyone's interested feel free to message me.