Have you ever wondered, "What transmission do I have?" As time marches on, technology changes. Classic car restoration is not a new hobby, and the older the project car, the more likely it is that someone has installed a different transmission at some point along the way. Modern 6-speeds are easy to spot, and 5-speeds are not difficult either, but when it comes to older 4-speeds and automatics, the increased variety can muddy the waters. So, whether you are heading out to check out a "For Sale" ad that could be your next project or trying to make heads or tails of a junkyard find, the following charts can be useful guides when it comes to GM transmission identification.