crank identification help

[taz]

A 400 crank externally balanced would have a counterweight on the flexplate . You could mesure the stroke remove a spark plug use a 1/4 drive extension run the piston to the lowest point that would give you a rough idea of stroke 3.48 for 350 3.75 for 400 you would have to guesstimatea little . Spin the engine by hand slow and to measure to avoid damage that will tell you what stroke you have . I built a 383 a couple of years ago and used an internally balanced crank . When in doubt measure . Oh and use a long enough extension please .
Tim