See more: Transmission Parts 5 Speed Big Twin
Mainshaft adapter spacer (S&S 56-1068)
The ZPN 750610 (S&S 56-1051) 5-into-4 transmission cases for 4-speed Big Twin style frames with 1970-1984 Shovelhead style drivelines and chain final drives is obsolete. They were used with a 1980 to early 1984 5-speed style chain-drive main shaft (ZPN 234729 or 234090) and 1980 to early 1984 style main drive gear (ZPN 234706 or 234578). The majority of the other internals are the same as for 1980-2006 5-speed Big Twin. Specific replacement parts are listed below.