Russ, that number doesn't show up in the 150 IPC's at all. Those IPC's show the inner strut as "NP". I guess it's the same problem in the 152 IPC.
I may have one in the hangar! It's from my 150C and may have been damaged in an off airport landing. I'll need to disassemble and inspect it today, and unless I find a number stamped on it, I have no way of knowing if it's right for your bird.
I googled the part number you gave and came up with only one good hit.
http://www.1stopaero.com/PDF/Cessna300400Parts.pdf0543006-5 TUBE $535.00 New Wasn't 316ZC in their clutches before you bought her? "Premier Aviation" sure rings a bell with me. Anyway, their inventory shows them as having a new one in stock, if the inventory is current. They seem to specialize in Cessna 300-400 parts, though.
Premier Aviation Sales and Services, LLC [
1stopaero.com]
Sanford, FL 32773
407-585-3549 Parts
407-585-3547 Fax