I own a 1964 Malibu SS Coupe 283/220 with 4 Speed. I purchased it in the fall of 1965 from the original owner, a close friend of mine. I put a 327 and new 4 Speed in the car in 1971. I have kept the original 283-4 Speed transmission and the coupe. Recently I was checking the casting number and part numbers on a couple of 4 Speed transmissions I have in storage. One of these was my original transmission. Checking in a book that I have "Chevrolet By The Numbers-The Essential Chevrolet Parts Reference" by Alan L. Colvin all the casting numbers match up, but the part number on the tag located on the side cover of my coupe I couldn't find in my Chevrolet Dealership Parts Book (dated 2-71) or in the "Chevrolet Parts Interchange Manual" by Paul Herd. Both have 3867265 listed as the transmission part number. The part number on the stamped tag of the original transmission is 3841435. I know the original owner so I know the car was picked up on March 27, 1964 at a Chevrolet dealer in Pennsylvania. I found this puzzling until I did some research in a book printed by Chevrolet that I picked up many years ago at a flea market called "Chevrolet Part History Dated January 1965 to April 1, 1970". I found part number 3841435 (the one on my transmission tag) was changed to part number 388676 in March 1965. The part number was changed again to 3867265 in September 1966. I don't know if this is common knowledge or not. I wonder how many people have questions about original transmission part number that they never have answered because they don't have one of these Chevrolet publications?