They are found on lots of farm trucks. Like Mike said, don't waste time on the 'net, need to get out there and look for yourself, also, don't bother asking, they don't care, look around and say I'll take these, don't show too much interest or the $ will go up.
Ed
I travel for business a lot (of course not right now) so I plan on stopping at the wrecking yards and look around. But seriously if anyone sees them out there especially in the lower states across the u.s...let me know.