I was quite fortunate to acquire a postwar baukarren from a Belgian militaria dealer. Wartime carts are EXTREMELY expensive, if you can even find one that is in good condition.
The cart came with leather straps for securing the backpack and poles, so it probably dated back to the early 1960s. Later carts had straps made out of canvas webbing.
The only problem with my cart was that the leather got dry, cracked, and brittle. At one event, a strap completely tore off when I tried to tighten it around some poles. The straps had to be replaced.
My local big box store sells tack (horse) supplies, including all sorts of small leather straps and hardware. It just so happened that curb straps and Chicago screws were perfect for repairing the baukarren.
I drilled out the rivets holding the old straps in place. I punched holes in the curb straps to accept the Chicago screws. I then fastened the new curb straps to the baukarren using the Chicago screws.
The curb straps work perfectly. If your baukarren has canvas straps, you can replace them with leather curb straps to make the cart more like a wartime cart.
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WW2 German Field Telephone Equipment 