This original "1984 - 1985 1/2 Hydraulic Diagnosis Supplement (HDS), Diagnosis and Unit Repair" was prepared by the Hydra-matic Division of General Motors Corporation.

The THM 440-T4 Hydraulic Diagnosis Supplement is a service publication designed to provide technical understanding and proper service of the Hydra-matic automatic transaxle

Sections include introduction, symbols and definitions, diagnosis procedures, modulator system evaluation, pressure and shift speed charts, range power flow, free check ball locations, electrical circuits, hydraulic circuits

Manual measures 8 1/2" ax 11"