What do the tech grades on discharge papers mean?

The "T-5" on your uncle's discharge papers means that at the time of his discharge from the Army, he was a Technician 5th Grade. The Technical Grades were used by the Army from 1942 to 1948. It was an attempt by the Army to recognize technical skills with an advancement in grade/rank, & pay. Your uncle's rank chevron would of been that of a corporal, but with a "T" beneath the chevron. A "T-4" would of been a sergeant, but with a "T" beneath the chevron. A "T-3" would of been a staff sergeant, but with the "T" above the "rocker" of the chevron. Finally, there was a "Technical Sergeant," which had no "T" on the chevron at all. Richard V. Horrell