I offer a Linkert M5 carburetor. Someone came across another type stamp No. 1 behind for the M5 mark. Why, I do not know.
For completeness, see the photo. The item "Harley Davidson Linkert M5 Carburetor Knucklehead U, UL, ULH M51" is in sale since Thursday, October 8, 2020.
This item is in the category "eBay Motors\Parts & Accessories\Motorcycle Parts\Antique, Vintage, Historic". The seller is "kaja750" and is located in Bílovice. This item can be shipped worldwide.