A tape measure and knowledge of part numbers is often the best way to identify a transmission. T-cases often have small plaques or tags that say what they are and help rule out errors, but these can be missing or may have been swapped between cases. Also, when buying early T-cases like a Spicer 18 or Dana 20, don’t forget to grab the output gear (A) that is bolted on the output shaft of the transmission. You’ll need it. Knowledge of intermediate shaft diameter of a Spicer 18 T-case (B) can make or break finding that perfect part for your early CJ or military restoration.