Squealing noise, 223 w/ 3 on the tree

Hi folks, I'm new to this site.(Damn glad I found it) I hope someone can help. I have a 64 F100. 223 w/ 3 on the tree. It's original w/ appx. 93,000 miles. The problem is that if I drive it much over 45 mph, it will squeal like a bad fan belt when I lift my foot off the gas. Step back on the gas and it stops. If I push in the clutch it It seems to gradually fade away as the engine speed reaches idle. I replaced the fan belt to no avail. My next guess would be a through out bearing.
Any other ideas before I get real dirty?

I appreciate any ideas. I'm sure I'll have lots more questions as I gradually restore this family heirloom.

Thanks

HAD A SIMILIAR PROBLEM WITH MY 54 223
IN MY CASE IT WAS BAD BEARINGS IN MY WATER PUMP. BOUGHT ONE OFF E-BAY. NO MORE NOISE.

Thanks for the advise.
Are there any recomendations in addition to e-bay for parts?

YES, HERE'S A BIG SURPRISE, NAPA. I WAS THERE YESTERDAY ABD THEY ACTUALLY HAVE A CATALOG FOR PARTS GOING BACK TO 1956
. ALSO CHECK OUT THESE GUYS AT www.lmctruck.com
THEY CARRY ENGINE PARTS FOR THE 223 (54-62)
YOU CAN ORDER A CATALOG FREE OVER THE INTERNET.

You're right that is a surprise. I appreciate the recomendation, and Michael Waltrip does too.