The Start
In the early 80s, Ford’s 6.9L diesel was equipped with the tried and true t-19 Borg Warner transmission. It was a four-speed and each forward gear was equipped with a synchronizer. The synchronizers aid in the synchronization or mesh of two gears to reduce or completely stop gear grinding when transitioning from one gear to another. This Borg Warner unit utilized a single countershaft and an idler shaft with the reverse idler gear. It had 10 square splines on the input shaft and measured 1 1/8-inch diameter. The t-19 was used by Ford and International in various applications and was the bigger brother to the t-18 transmission. The T-19 provided a low first gear ratio of 4.02:1. Fourth gear was direct or 1:1 ratio. Chevy equipped its light-duty diesel, the 6.2L, with the proven SM465 made by Muncie. The 465 had similar features to the T-19. The 465 had a 1 1/8-inch diameter input as well with 10 splines and featured a 19/32-inch end for the pilot bearing. They are both cast iron units, both used synchronizers between the gears, and both were top-load transmissions. This last feature made them very desirable when it came time to rebuild them. The SM465 decided to not synchronize low gear or reverse in their transmission. Low gear for the SM465 received a very low ratio of 6.55:1. As the years progressed, Dodge decided to place a diesel engine in its 1989 model pickup trucks. The Cummins engine was the power plant of choice by Chrysler and the German made Getrag G360 five-speed transmission was the manual transmission coupled to it. It had very similar features to that of the SM465 and t-19 transmissions aside from one special characteristic, an overdriven fifth gear.