The MY6 is a rugged 4-speed manual transmission with overdrive (often called the NP440 or "New Process 833") used in 1981–1987 GM half-ton trucks, frequently paired with 6.2L diesel engines.
MY6 is also very high geared in 1st & reverse.
They came along about a year into my GM wrenching career. Most customers were less than thrilled with them.
Rancher uncle had one, low range was required most the time any terrain encountered to keep from burning the clutch out.
In places with less terrain it's a good transmission.
