NP231 splines

[stevehayden]

Does anyone know which year had 23 spline and which had 21 spine?

 

[89wrangler]

88/89 cherokees/YJ were 21 spline. The YJ 2.5 with the 5 speed was a 21spline. There was a switch over in mid 89 The BA10 had 21 spline and the AX15 23 spline. IIRC