It looks like per the 2007 parts catalogue that it should be an Ameritool 10-296 pneumatic shock, which shows as a 10-30#. I'd obviously call up Ameritool to confirm, as a quick Google search doesn't show any new products with that same part number, as it's likely an older or discontinued one. There's a "gas spring guide" on page 162 of the parts catalogue that gives you the specs on all of the springs. A 10-296 is a 30lb shock with a rod diameter of 0.25", a body diameter of 0.625", a stroke of 3", compressed length of 7", extended length of 10" and as mentioned a lift of 30lbs. I'd definitely measure yours out and double check first, but I imagine that's going to be the correct one. A quick call to Ameritool can likely get you a replacement. Good luck.
GW P.N. ROD DIA ( A ) BODY DIA ( B ) STOKE ( C ) COMPRESSED LENGTH ( D ) EXTENDED LENGTH ( E ) LIFT (LBS)
10-0191 0.25" 0.625" 3" 7" 10" 30
10-0192 0.25" 0.625" 2.25" 5.25" 7.5" 15
10-0236 0.312" 0.750" 6" 9" 15" 20
10-149 0.312" 0.750" 6" 9" 15" 125
10-295 0.25" 0.625" 2.25" 5.25" 7.5" 60
10-296 0.25" 0.625" 3" 7" 10" 30
10-297 0.25" 0.625" 2.25" 5.25" 7.5" 30
10-661 0.312" 0.750" 6" 9" 15" 40
10-674 0.312" 0.750" 4" 8" 12" 100
10-675 0.25" 0.625" 3" 7" 10" 60
10-677 0.312" 0.750" 4" 8" 12" 80