(the singular is Passstufenstift)

My interpretation: a Passstift is an alighment pin or dowel pin, and a Stufenstift is a stepped dowel pin (a dowel pin with two different diameters).

Refs (Gernan refs for 'Stufenstift' are rare at best):

UR
Many of our flywheels now include stepped dowel pins. The advantage of stepped dowel pins is that if a pin were loosened during installation, ...
www.unorthodoxracing.com/uL.html

These entries are given in the order of the letter following the ...... connector socket, plug); die Anschlussstiftleiste (terminal pin strip) ... der Passstift (dowel, dowel pin, locating pin); das Passstück (adapter, ...
www.cs.utsa.edu/~wagner/german/sss2.html

These entries are given in the order of the letter following the ...... connector socket, plug); die Anschlussstiftleiste (terminal pin strip) ... der Passstift (dowel, dowel pin, locating pin); das Passstück (adapter, ...
www.cs.utsa.edu/~wagner/german/sss2.html

[PDF] A 5000
6 0053983 1. Shaft seal. Wellendichtring. Sello del eje. Bague d'étanchéité. 7 0053995 2. Dowel pin. Passstift. Espiga. Cheville. A8 x 14. 8 0107063 6 ...
www.company.wackergroup.com/.../04Modulare_Innenruettler/ Modulare_Innenruettler_A_5000_ersatz.pdf
Online Ordering - Bishop-Wisecarver
SL2 STAINLESS DOWEL PINS, Print this page ... Name, Description. SSSDP4, SS STEPPED DOWEL PIN. SSSDP6, SS STEPPED DOWEL PIN. SSSDP8, SS STEPPED DOWEL PIN ...
www.bwc.com/inventory.php?level1=300& level2=3950&prod_type_no=40

Industrial Pins Information on GlobalSpecParallel dowel pins have ends that are machined to two different tolerances. Stepped dowel pins have two different body diameters altogether. ...
mechanical-components.globalspec.com/LearnMore/ Mechanical_Components/Mechanical_Fasteners_Hardware/Pins