What is the name of the male valve on built in tanks??

You have a ASME tank fill valve. USE ASME when checking on connections.
Below is a link that should fit the RV.
https://www.ebay.com/itm/191130398995?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=191130398995&targetid=1263433204774&device=c&mktype=&googleloc=9027230&poi=&campaignid=14859008593&mkgroupid=130497710760&rlsatarget=pla-1263433204774&abcId=9300678&merchantid=6526494&gclid=CjwKCAiAvaGRBhBlEiwAiY-yMHs00HkG-LfyOnRKmo--OhKmEOXIbL-0eFB4oxes2bkLbZtdlrYInxoCbAQQAvD_BwE



FILLER VALVE 7647SC
Brand: Aftermarket
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$29.02
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3/4'' NPT FOR FORKLIFT AND ASME TANKS
Hose Connection1 3/4" ACME
Tank Connection M. NPT3/4"
Wrench Hex Flats1 3/4"
Effective Length2 1/4"