TM 10-3930-660-34 9-5 . REAR DIFFERENTIAL CARRIER ASSEMLY - REPLACE/REPAIR/ADJUST (Cont’d) NOTE If a new bevel pinion (29) and ring gear (18) set is installed ,  or if the depth of the bevel pinion (29) has to be adjusted ,  calculate the needed thickness of the shim pack using the following procedure: a. Use a micrometer to measure thickness of old shim pack (34) removed from under bearing cage (30) .  Record measurement. b. Read cone variation number on spigot end of old bevel pinion (29) .  Record number. NOTE Bevel pinion spigot end number can be in 1,000ths of an inch or 100ths of a millimeter .  Millimeters will be indicated with a decimal point .  Example: +3 = .003 inch ,  +.03 = .03mm .  Be sure to convert millimeters to inches by multiplying by 0.039 before performing the following calculations: c. If old bevel pinion cone number is a plus (+) value ,  subtract number from shim pack (34) thickness measured in STEP a. If old bevel pinion cone number is a minus (-) value ,  add number from spigot end of old bevel pinion (29) to shim pack (34) thickness .  This is the thickness of the standard shim pack , without a cone variation. d. Read number on spigot end of new bevel pinion (29) .  Record number. 9-18