I went to see a guy who spent almost $30K on a truck and then put it up for sale. A gorgeous, totally rebuilt and original truck. I asked him why he was selling it. He said he and his wife went on a trip to a car/truck show. He won first prize. On the way home his wife said she didn't like riding in the truck. It was too noisy and rode stiff.
The Hydramatic doesn't have a torque converter. GM designed-in a low first gear to get the truck moving. First to second happens quickly. Changing from 3:90 to 3:38 may affect the truck initially moving. I suspect it would be okay unless you were hauling a load.
Is your truck V8 or I6?
