J numbers on a 409...what do they mean?

[Mr.Jimmy]

Hey guys,


Reading about the 61 block made me think about the "J code" on the left hand side of the motor by the oil filter area. I have looked at over 75 409 motors and blocks and can't figure out what this stands for. I have see different J codes from J 1 through J 27. Fran and you other guys, what does this stand for?????

[Fran Preve]

MrJ: wish I could help, gears guess is as good as any.

[real61ss]

Mr. Jimmy,
I have no idea what the j number means either, mine has a J-2 I beleive. The motor is in the shop so I can't go look at it. That's a cast number, the number that bugs me is the stamped numbers at the rear by the distributor. I'll try to post a picture.

[Fran Preve]

GM 5 looks like a pattern number. Couldn't tell you the Y27.