This petcock is harder to find than the smaller threaded bung type of 1977 tank. The earlier tanks are obviously more common, but the petcocks for them sell for $75!
I have a used petcock I bought on ebay for $45 and am now selling on ebay for $45.00.
Sure beats buying a new one for $75.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=230637070905&ssPageName=STRK:MESELX:IT#ht_500wt_1182
I have a used petcock I bought on ebay for $45 and am now selling on ebay for $45.00.
Sure beats buying a new one for $75.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=230637070905&ssPageName=STRK:MESELX:IT#ht_500wt_1182