The 3 first numbers/letters labelled on parts (like on CDI for example) or of part N° (on microfiche) show the model code of the bike for wich one this part was created.

Example: on the '86 RD350F2 the windscreen is labelled "57V" and the part N° reference on microfiche is "57V - 283703 - 00". So the following chart show you that this part was created in '85 for the RD350F model. So you know that you can use a second-hand RD350F windscreen on your RD350F2...

Other example: on the RD350F2, the front/rear light, water temperature gauge, tachometer, rectifier/regulator have part N° beginning by "47X" and "47X" is the model code of RD500LC so it permits to know we can use second-hand parts of other bikes wich are common with the RD/RZ350LC...

Here are typical parts stamped with model code: cylinder, cylinder-head, carburettor, exhaust pipe, CDI and windscreen .

Be carefull with the oil pump: the pulley is stamped 4L1 on all RD350LC's but on YAMAHA microfiches, part N° are different depending of models 4L0/31K/1WT..., so settings can be different.
 

MODELS	POWER	PART N° START / MODEL CODE	COUNTRY	YEAR
RD 350 LC	47	4L0	Europe	'80
RD 250 LC	35	4L1	Europe	'80
RD 350 H	47	4Y3	Canada	'81
RZ 350 R	59	29K	Japan	'83
RZ 250 R	59	29L	Japan	'83
RD 350 LC2	59	31K	Europe	'83
RD 350 LC2	50	31W	Germany	'83
RZ 350 K	59	33E	Canada	'83
RZ 350 RR	59	52Y	Japan	'84
RZ 250 R	45	1AR	Japan	'84
RZ 250 RR	45	51L	Japan	'84
RZ 350 N	52	48H	USA	'84
RZ 350 NC	52	1EL	USA/California	'85
RD 350 N	59	1JF	Europe	'85
RD 350 F	59	57V	Europe	'85
RD 350 N2	63	1UA	Europe	'86
RD 350 N2	50	1XA	Germany	'86
RD 350 N2	27	1XE	Germany	'86
RZ 250 R	45	1XG	Japan	'86
RD 350 N2	59	2UA	Italy	'87
RD 350 F2	63	1WU	Swiss	'86
RZ 350 S	63	1WV	Canada	'86
RD 350 LC	55	1YH	Brazil	'86
RZ 350 U	63	3FB	Canada	'88
RZ 250 R	45	3HM	Japan	'88
RD 350 R	55	4CD	Brazil	'92

 

Here are some parts marking wich will help you to identify some spare parts or if the right OEM parts are on your motorcycle

for models in Europe

Europe (Germany)	RD350LC '80 to '82 4L0	RD350LC2 '83 to '84 31K (31W)	RD350F/N '85 57V/1JF (1AG / 1JG)	RD350N2/F2 '86 to '90 1UA/1WT/3DH1 (1WW/1WX/1XA/1XE)	RD350R '92 4CE4/5 Italy/Spain	RD350R '92 4CE6 UK
Cylinders	4L0	31K	31K	1UA	1UA	1UA
Carburettors	4L0	31K	31K	1UA	2UA	4CE
		For Germany 31W for 50HP model	For Germany 31W for 50HP 1AG / 1JG models	For Germany 1XA for 50hp 1WW/1XA models 1XE for 27HP 1WX/1XE models 1WU for Switzerland	-	-
Exhaust pipe	4L0 - 14711 4L0 - 14721	31K - 14711 31K - 14721	31K - 14711 31K - 14721	1UA - 14711 1UA - 14721	1UA - 14711 ? 1UA - 14721 ?	4CE6-1 4CE6-2
	For Germany	31W - 14711 / 14721 for 50hp model		1XA - 14711 / 14721 for 50hp 1XE - 14711 / 14721 for 27hp	-	-
CDI	070000-0720	29K-50	52Y-50	1UA-50	4CE-00	4CE-00
Ignition rotor	VCC 27	29L-50	51L-50	VCD-88	VCD-88	VCD-88
YPVS control unit	-	29L-M0	51L-M0	1UA-00 51L-M0 for 1WU	1UA-00	1UA-00

On 51L & 1UA controllers the references are often erased but you can identify them with the electric sheath which are black & white for 51L and black & blue for 1UA