On the hood it has Hydramatic just like all of the smaller series trucks. The original transmission was removed because of oil leaks and replaced by a muncie 5 speed manual. I would like to find the original auto trans to restore the truck though. The truck was originally purchased by the Caterpillar dealership here in Greenwood in 1955 and was their lo-boy truck, so they told me it had a hydramatic. The engine is either an olds or pontiac V8, it has air brakes, and power steering. I am not familiar with the hydramatic, so were there different size tranmissions for the larger series trucks or were they all the same? Does anyone know where I can find any information about 550 series GMC's on the internet. Thanks for any replies.
