Napoleon1991

I recently had the rear end gears in my cutlass changed so I ordered the correct speedo gear to adjust the speedometer reading. The gear I was sent fits the trans fine, but the square hole that the speedo cable fits into is too big. The guy i bought it from said that it was the correct gear for a th350 which is what I have, so im not sure why its the wrong size. Is there an adapter I can buy, or do I just have to try and order a gear from someone else and hope that it fits?