Does this help?
Crankcase Identification Numbers
Numbers located on both left and right
crankcase halves.
Big Twin: Left Case - Outside, Lower Front
Right Case - Inside, Gearcase Compartment
XL Models: Left Case - Inside,
Primary Compartment
Right Case - Outside, Near Oil Pump
Stamped at Capitol Drive Facility
Used to identify engine and track
production changes
Example: 1588 321 007
15 = Engine Designation
1 = 1200cc Shovelhead
7 = 1000cc Iron XL
14 = 1340cc Shovelhead
15 = 1340cc Evolution
16 = XR-1000
17 = 883cc Evolution XL
18 = 1100cc Evolution XL
19 = 1200cc Evolution XL
20 = 1340cc Evolution,
California (1988 - *)
21 = 883cc Evolution XL,
California (1988 - *)
22 = 1200cc Evolution XL,
California (1988 - *)
88 = Model Year
321 = Day of Production:
001 = Jan. 1st 182 = Jul. 1st
032 = Feb. 1st 213 = Aug. 1st
060 = Mar. 1st 244 = Sep. 1st
091 = Apr. 1st 274 = Oct. 1st
121 = May 1st 305 = Nov. 1st
152 = Jun. 1st 335 = Dec. 1st
007 = Number That Day
Thanks for the info gotta check that out when i get home.