Interactive Tool

Muncie 4-Speed Identification Tool

Rule-based scoring tool for M20, M21, and M22 identification. Use this as a screening tool, then confirm with serial/date code checks and physical inspection.

Casting Number Gear Noise Type Vehicle Year (Optional)

Case Features (select all that apply)

Coarse input spline Fine input spline Drain plug case P7 case marking Heavy-duty side cover Wide-ratio road behavior Close-ratio road behavior

Results

Enter your clues and submit the form to estimate whether the transmission is most likely an M20, M21, or M22.

This is a rule-based helper, not a final authentication. Always verify with serial/date codes and in-person inspection.