Here are some pictures of the "Beguine" P-51.

http://www.esparacing.com/aircraft%2...P51Beguine.htm
and
http://www.pylon1.com/airracers/airc...focus/beguine/

From the Pylon1.com link above:
"The idea that Walter Beech wanted in it was to incorporate the radiators in a wing-tip nacelle so you get a little jet effect from it. All a jet engine is: you build a fire in the middle of a nacelle - by putting the radiators in the nacelles we got a little jet effect and overcame the drag of the nacelles as well as cleaned-up the wing-tips. That was Walter's idea on that. When I told Paul what Walter wanted he said "Well J.D., that's a crazy idea! We ought to sink the radiators in the leading edge of the wing - that would be the cleanest". I said, "No Paul, I want them in a nacelle on the wing-tip. I want you to shorten the left wing 24 inches and I want you to shorten the right wing 30 inches, that's what Walter wants." And so he says, "J.D. you know, that's crazy! I'm going to have to fly this airplane!" I said, "Well, if you don't want to do it pack-up and come on home and I'll send somebody else out there that will do what I want." Paul then said, "Well, OK I'll do it, I'll do it." So he built the airplane with the nacelles."

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As for Rare Bear's prop, here is the history from John Slack (from AAFO.com):

Propeller goes as follows:
1969,1970 Stock stock length DC-7 Prop/C&S propellers
1971-aproximately1986, stock Aeroproducts propeller with M20A- 162-0 blades.
1986-1990 Stock Aeroproducts propeller with H20G-162-0 blades.
1990-2002 Highly modified P-3/Constellation propeller.
2003 Thats the secret now isn't it?

As stated before M20A-162-0 blade has the cuff on the trailing edge, H20G-162-0 blade has no cuff. Rare bear has never had a cut down Skyraider propeller.
John Slack