18 spline or 23 spline tranny

[69pistolgripRT]

Is there an easy way to determine which I have with the engine and tranny already installed in the car?

[MOPARHOUND!]

There should be a 3 digit ink stamp on the passenger side of the trans, about 3 inches tall, usually in white, yellow, or blue paint.  It is stamped high on the passenger side, and may be difficult to see in the car due to the tran's tunnel.  Might use one of those mechanic mirrors that the shaft extends and the head flexes on.

Is the full V.I.N. stamped on the pad on the passenger side??

What is the casting number on the tailshaft  of the trans?

[Ghoste]

I'm not 100% positive on this but I THINK that if you have any of these part numbers, it's a Hemi (18 spline) box.
2538388, 2538399, 2892047, 3410610, 3410683, or 3410761

[John_Kunkel]

With the tin dust cover removed you can see part of the input shaft splines.