decode number 12 grader serial number

That would be hard with that serial number. CAT serial numbers are in a format like 8T3900 or 70D14553. The older series all stopped at 9999, but later ones could run to 5 digits.

You should have a 6 cylinder engine............ is the intake manifold on the same side of the engine as the exhaust or are the manifolds on opposite sides?

Opposite sides = D318 made 1947-1959/60? (or possibly D333 or 3306 even if the pony mounts on the side of the engine instead of on the top of the flywheel housing)
Same side= D4600 made before 1947. pony motor mounts on back of engine on top of flywheel/clutch housing.

Look again for a serial number tag on the main frame of the grader, sometimes on the left front side ahead of the blade or maybe on the right side ahead of the cab, but behind the blade. Also on the engine, near the pony motor controls usually riveted on just below the head gasket line.

Or put up some pictures. We like pictures😆

Right you are that second number is not a number it is the letter T. Should have put my glasses on the first time. 😊. Manifolds are on opposite sides.

You missed the oil clutch by about a year. I have it listed as starting at 16361 in 1955.

Thanks much for the info guys.... Well I played around with it a bit today and it sure seems to work good. I will try loading some pics. [attachment=19403]image.jpg[/attachment][attachment=19404]image.jpg[/attachment][attachment=19405]image.jpg[/attachment][attachment=19406]image.jpg[/attachment][attachment=19403]image.jpg[/attachment][attachment=19404]image.jpg[/attachment][attachment=19405]image.jpg[/attachment][attachment=19406]image.jpg[/attachment]

Breakdown on the 8T:
12 Motor Grader diesel tandem drive 8T1

1947............1-1139
1948...........1140-2250
1949............2251-3724
1950.............3725-6550
1951............6551-9000
1952...........90001-11130
1953...........11131-12220
1954............12221-14800
1955...........14801-17239 (16361 begin oil clutch)
1956...........17240-20500
1957.........20,501-21904

http://www.chriscomachinery.com/Graders.htm

Breakdown on the 8T:
12 Motor Grader diesel tandem drive 8T1

1947............1-1139
1948...........1140-2250
1949............2251-3724
1950.............3725-6550
1951............6551-9000
1952...........90001-11130
1953...........11131-12220
1954............12221-14800
1955...........14801-17239 (16361 begin oil clutch)
1956...........17240-20500
1957.........20,501-21904

http://www.chriscomachinery.com/Graders.htm

Line your pics. up the right way when you scan so we don't have to stand on our heads or lay on our sides to view. Thank you. catskinner