What is this shower cartridge?

Can someone please id this shower cartridge?

There are unfortunately a million that all look alike. If you go to this link: www.alfanoplumbingparts.com and scan thru the cartridges catalog, the unique features to compare are diameter,overall length, number of "teeth" on the splined shaft, and the distinct shape of the bottom blue gasket . Give us some overall photos of the valve and trim to help us out.

old style Gerber (most likely because the colors are the same), although it appears to be similar to several other "old style" cartridges which all probably used the same core. None of them, however, have the long shank that yours appears to have, unless it is just a bad picture.

hj said:

old style Gerber (most likely because the colors are the same), although it appears to be similar to several other "old style" cartridges which all probably used the same core. None of them, however, have the long shank that yours appears to have, unless it is just a bad picture.

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The picture is fine and a true representation. I have seen similiar cartridge on the previous comment's site but with shorter shank, which may be used in a faucet as opposed to a shower. What happens if I really can't find this cartridge anywhere? Do I need to take the whole assembly out of the shower valve casing and replace with something on the market?