Here are three versions of the early Sportster cover (57-68). ¹⁾
These covers have a screw mechanism that pushes a rod that goes through the transmission and actuates the clutch.
The 1957-1966 XLH and 1957-1967 XLCH covers actually have three different variations.
On the earliest K-model version, the rib continues on the other side of the clutch actuator.
The XLCH style has a -52B casting number. The corresponding XLH part has a -67 casting number.
Be careful not to confuse casting numbers with part numbers. Although they occasionally correspond, they most often don't.
Early and later Sportster versions differ in the angle of the zerk fitting boss.
The 1967 XLH cover continues the ribbed design, but has a cutaway for the electric start (one year only).
The 1968-up XLH version has the cutaway for electric start. This piece may have been introduced mid-model-year in 1967.

Three sprocket cover versions for 1952-1968 2)

1957-1966 XLH and 1957-1967 XLCH Cover 3)	1968-1969 XLCH cover 4)	1968-1969 XLH Cover 5)

Sprocket Cover (34869-70), without kick starter.
Click on a pic to enlarge ⁶⁾

Sprocket Cover (34871-67B), with kickstarter. This cover was sold in 1971 as a replacement for 1967-1970 XLH models.
Click on a pic to enlarge ⁷⁾

Sprocket Cover (34870-71), polished, without kick starter.
Click on a pic to enlarge ⁸⁾

Sprocket Cover (34870-73), black, without kick starter.
Click on a pic to enlarge ⁹⁾

Sprocket Cover (34868-75), polished, without kick starter.
Click on a pic to enlarge: ¹⁰⁾

Original Outer Sprocket Cover (34870-75) for 1977-1978 XL/XLH, polished, without kick starter.
Click on a pic to enlarge: ^{11) 12)}

Replacement Outer Sprocket Cover (34870-75A) for 1977-1978 XL-XLH, polished, without kick starter. ¹³⁾

Outer Sprocket Cover(34870-79), polished, without kickstarter.
Click on a pic to enlarge: ¹⁴⁾

Outer Sprocket Cover (34872-79), polished, with kichstarter.
Click on a pic to enlarge: ¹⁵⁾

Original Outer Sprocket Cover(34870-79), factory painted silver, without kickstarter.
Click on a pic to enlarge: ¹⁶⁾

An Inner Sprocket Cover (34899-79) was used for all 1979 model Sportsters. The pic below is of a used inner cover. ¹⁷⁾