There are 2 differents appellations (of models) given by YAMAHA for it 350LC: one for the brochure (commercial appellation) wich can be the same on the bike and an other for the YAMAHA service/owners manuals.
3 examples:

 

'84 & '85 USA RZ 350 or RZ 350 L/N/NC/N2/NC2
'86 Canada RZ350R or RZ350S
'86 Europe RD350F or RD350LCF et RD350 or RD350LC

A third appellation is given by owners (in Europe) wich is an extension of the brochure appelation.

RD350LC2 for the '83 YPVS as the evolution of the '80 to '82 RD350LC(1).
RD350N2 for the '86 YPVS Naked as the evolution of the '85 RD350N(1).
RD350F2 for the '86 YPVS Faired as the evolution of the '85 RD350F(1).

In England, the "ELSIE" (LC) is still very popular and there is some typical following English appellations:

LC or pre-powervalve for RD350LC(1)
LC2 or YPVS or Powervalve for '83 to '84 RD350LC2
N for '85 Naked RD350N(1)
F for '85 Faired RD350F(1)
N2 for '86 Naked RD350N2
F2 for '86 Faired RD350F2
R for '92 to '95 Brazilian made RD350R

The best way to define the model (4LO, 31K, 48H, 1EL...) is to read the VIN # or Engine or frame number.