68-70 Dodge A100 3speed manual speedo info needed

A friend has a 68-70 dodge A100 van. it is a 318/ 3speed manual. He changed the center section from 3.55 to 2.94 a while back. Now his speedo is off (speedo gear needs to spin faster.)
Here's the weird part. The speedo gear goes into the transmission on the passenger side of the transmission & it does not look like there is the aluminum adapter ???
Anyone have any idea what trans he has ??? Also can you change the speedo gear in the transmission/ to correct the speedometer needle being wrong ???