i dont think anyone makes an aftermarket one. i made mine out of less than 20$ worth of pvc. my hood is trash("speed holes" left over from firemans pick ax) so i chose to cut out the the hood back by the firewall just to the side of the brakebooster and run it out there. if you still have the springs on your hinges,im not sure how well it would stay up if you cut out the back support like i did. i connected it to the stock air cleaner with a 4"x2" rubber pvc adapter. this was the most expensive part at $5.49. i used 3 big c clamps to keep the air cleaner housing pressed tightly together. i made a small snorkel out of 1 inch pvc and attached all the vents to it-both diffs,transfer case,trnsmission,carb. some power steering pumps have vented caps,you could attach that one too.
anyway,it works good enough for me to cross 5-6 feet deep creeks,and the hood completely disappear underwater for several seconds. i looooooove the water...
let me know if youd like any further details.
85 grand wagoneer
258 with motorcraft 2bbl/904/twin stick dana 300/dana 44/welded amc 20
38x15.5 gumbo mudders
snorkel/dual batteries/onboard air/"custom" convertable
3 inch body lift/mostly stock suspension/"modified" fender openings
custom front/rear bumpers and brushgaurd
possible small block chevy "test" swap in near future