All part numbers were gathered from period specific Sportster parts catalogs from 1957-1985 including supplement and updated catalogs.

Year Model	Part Number	For Kickstart?	Casting Number	Notes
1952-E1954 K Models	34876-52 1)	Yes	34874-52
Additional notes	It is believed the MoCo made a running change in mid 1954 when they changed worm gears. 2) The sprocket covers were sold as “complete”. So the new worm gear should have been installed in a new cover part#.
L1954-1956 K Models	34876-52A 3) 4)	Yes	34874-52	Replaced by 34876-52B (1957) Replaced by 34876-52A (1958) Used 34876-52A (1959-on)
1957 XL	34876-52B 5)	Yes		Replaced by 34876-57 (1958) Replaced by 34872-57A (1970) 6)
Additional notes	See Pic section below.
1958-1962 XL/XLH/XLC/XLCH	34876-57 7)	Yes	34874-52A	Replaced by 34872-57 (1963) Replaced by 34872-57A (1970) 8)
1963-1966 XLH/XLCH and 1967 XLCH	34872-57 9) 34872-57A	Yes	34874-52A 74-52	Replaced by 34872-57A For 1967 XLCH only (1968) 10) For all models (1970)
1967 XLH	34871-67 11)	Yes	79-67	Replaced by 34871-67A (1969) Replaced by 34871-67B (1970)
1967-1970 XLH	34871-67B 12)	Yes	79-67B	Offered in 1971
1968-1969 XLH	34869-68 13)	Yes	79-67A
1968-1969 XLCH	34872-57A 14)	Yes	74-52
1970 XLH	34869-70 15)	No	79-67B
1970 XLCH	34872-70 16)	Yes
1971-1972 XLH	34870-71 17)	No	34879-71	Polished.
1971-1972 XLH	34871-71 18)	Yes	34879-71	Polished
1971-1972 XLCH	34872-71 19)	Yes	34879-71	Polished. Replaced by 34872-71 (1975)
1973 XLH	34870-73 20)	No	34879-71	Black. Kick cover 34871-71 (offered 1976)
1973 XLCH	34872-73 21)	Yes		Black
1974 XLH	34870-71 22)	No	34879-71	Polished. Kick cover 34871-71 (offered 1976)
1974 XLCH	34872-71 23)	Yes		Polished
1975-1976 XLH	34868-75 24)	No	34879-71	Kick cover 34871-71 (offered 1976)
1975-1976 XLCH	34896-75 25)	Yes	34879-71
1977-1978 XL/XLH	34870-75 34870-75A	No	34879-75 or 34876-75 34876-75A	Outer cover Replaced by 34870-75A (-78A cat)
1977-1978 XLCH	34872-75	Yes	34879-75	Outer cover
1977-1978 XL/XLCH	34893-75	N/A		Inner cover
1979 XLH	34863-79 26)	No	34879-79A	Outer cover
E1979 XLCH	34872-79 27)	Yes	34879-79A	Polished outer cover
1979 XLS	34870-79 28)	No	34879-79A	Outer cover
1979 XLH/XLCH/XLS	34899-79 29)	No	None	Inner cover
1980 XLH	34911-80 30)	No		Polished cover. Replaced by 34918-81 (1983)
1980 XLS	34912-80 31)	No		Black cover. Replaced by 34915-81 (1982) Replaced by 34915-81A (1984)
E1981-1982 XL	34918-81 32)	No		Polished cover. Replaced by 34918-81A (1984)
L1981-1985 XL	34911-81 33)	No		Polished cover. Replaced by 34918-81A (1985)
E1981 XLS	34915-81 34)	No		Vivid black cover. Replaced by 34915-81A (1985)
L1981-1982 XLS	34912-81 35)	No		Black cover
1983-1984 XLS	34911-81 36)	No		Polished cover
1983-E1984 XLX	34908-83 37)	No		Aluminum finish cover
L1984-1985 XLX	34908-83A 38)	No		Painted cover

The part number for these sprocket covers DOES NOT APPEAR on the cover.
The casting number is visible on the inside of the covers as well as described in the chart above and the pics below.
The casting number is the same for many covers as that is the base construction of many of them (even though there are still differences between them).
See also HD Part Numbers Explained and HD Casting Numbers, Letters and Symbols Explained in the Sportsterpedia.

Every Ironhead sprocket cover has a casting number, else it's not a factory part.
Likewise, aftermarket covers do not have HD casting numbers.

The stop pin (roll pin) is in the cover (underside). Look closely at these as they have a tendency to shear off flush with the cover.
The early covers were drilled through at the roll pin and you could drive it out from the outside. ³⁹⁾
1968-1970 covers have a boss added to the underside in a wider girth around the worm gear.
The hole for the roll pin is drilled from the underside, through the boss, but not all the way through to the outside of the cover.
This makes removing a broken off roll pin harder.

Cover part# change between 1957 and 1958:
Cover (34876-52B) shows up for the first time in the -57 parts catalog for all 1952-1956 K Models and 1957 XLs.
And the -52A cover was replaced by the -52B cover.
However, the -58 parts supplement catalog labels the -52B cover as “not used, Replaced by 34876-57”.
And for 1952-1956 K Models, cover -52B was replaced by cover -52A, which was already on K models since L1954.
And the -58 catalog also shows the 34876-52A cover as replacement for K Models, not the -52B cover.

Sprocket Cover part# (34876-57), with kickstarter. The casting number is (34874-52A).
Features and changes:
The angle of the worm gear grease (zerk) fitting changed to (angled forward 1:00) as opposed to the vertical position on the K Model covers.
The grease fitting is threaded into the boss.
Also the grease (zerk) fitting position for the kick starter crankshaft was moved to the (9:00) position.
A boss is cast into the cover at the (9:00) position as extra strength for the grease fitting which is pressed in.
The pin stop for the worm gear is simply pressed into a hole drilled through the cover at an angle.
The center cavity under the bar on the cam cover side resembles the back side of an arrow.

Pics of used covers. Click on any pic to enlarge:
^{40) 41)}

^{42) 43)}

Sprocket Cover part# (34872-57), with kickstarter. The casting number is (34874-52A).
Features and changes:
The grease (zerk) fitting position for the kick starter crankshaft was moved to the forward side of the bushing hole (1:00).
A long angled boss was added off the crankshaft bushing bore for the new grease fitting location.
The 1962-previous boss is still present at the (9:00) position but it is not drilled out for a fitting.
The pin stop for the worm gear is pressed into a hole drilled through the cover at an angle.
The center cavity under the bar on the cam cover side resembles the back side of an arrow.

^{44) 45) 46)}

The 1967 XLH cover continues the ribbed design, but has a cutaway for the electric start (one year only). ⁴⁷⁾
Sprocket cover part# (34871-67), with kickstarter, the casting number is (79-67).

The original 1968-1969 XLH cover is HD part# (34869-68), with kick starter. The casting number is (79-67A).
The ribbed design matching the cam cover was removed for a smooth surface across the cover instead.
The worm gear roll pin bore does not go all the way through to the front of the cover.

Below are pics of a used 68-69 cover. Click on a pic to enlarge.

^{48) 49) 50)}

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

^{51) 52)}

Additional pics

^{53) 54)}

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 ⁵⁵⁾

Sprocket Cover (34870-71), polished, without kick starter.
Click on a pic to enlarge ⁵⁶⁾

Sprocket Cover (34870-73), black, without kick starter.
Click on a pic to enlarge ⁵⁷⁾

Sprocket Cover (34868-75), polished, without kick starter.
Click on a pic to enlarge: ⁵⁸⁾

Original Outer Sprocket Cover (34870-75) for 1977-1978 XL/XLH, polished, without kick starter.
Click on a pic to enlarge: ⁵⁹⁾

Replacement Outer Sprocket Cover (34870-75A) for 1977-1978 XL-XLH, polished, without kick starter. ⁶⁰⁾

Outer Sprocket Cover(34863-79), polished, without kickstarter.
Click on a pic to enlarge: ⁶¹⁾

Outer Sprocket Cover (34872-79), polished, with kichstarter.
Click on a pic to enlarge: ⁶²⁾

Original Outer Sprocket Cover(34870-79), factory painted silver, without kickstarter.
Click on a pic to enlarge: ⁶³⁾

An Inner Sprocket Cover (34899-79) was used for all 1979 model Sportsters. The pic below is of a used inner cover. ^{64) 65)}