There are two different ones I have come acrossed. The ones you have & the correct ones that actually work & slide right in. I thought I had bought both sets at the same place but then I remembered I had bought the right ones from some place back east or mid west but can't remember where. I will ponder on this as I need to get a set for my 1948 as well.

"IT IS WHAT IT IS"
1953 Chevrolet 1/2-ton 3100 4x4
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1948 GMC 1-Ton (now sold to someone in Hawaii!)
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1953 Chevy 1-Ton