Your 150M (s/n 15076916) would be either Usable On Code A or D.
P/n 0752037-3 elbow is the correct part for your plane.
As I'm sure you know, Cessna is very proud of these, There is one on eBay.
0752037-2 on eBay [
ebay.com] This is apparently new in the package. I do not think it is a restricted fitting.
The standard AN816 fitting is a straight fitting and is NOT restricted, and should work fine. The "-2" indicates it is for 1/8" tubing (37° flare side), and the "B" indicates it is copper alloy (not available for decades). Ask your mechanic if he could use a standard and far less expensive AN816-2D (aluminum alloy) straight fitting, unless he insists on the exact Cessna part for your A/C serial number.
