Brother, this is the research conducted by Danyal a.k.a ACE.
The Toyota Land Cruiser Nomenclature
Consult the diagram attached below for easy reference.

It turns out that these are all “codes” that Toyota uses to distinguish between different features of its different Land Cruiser models. They are all part of the Toyota Land Cruiser Nomenclature. Each word and each letter has a different meaning.
HZ=1HZ
PZ=1PZ
B=3B, 13B-T
HD=1HD-FTE
J=Jeep / Off-road
4=40-series
6=60-series
7=70-series
8=80-series
0-2=Short Wheel Base
3-4=Middle Wheel Base
5-9=Long Wheel Base
L=Left Hand Drive
R=Right Hand Drive
Blank=Soft Top
V=Hard Top, FRP Top
P=Pickup
Z=High Roof (applies only to 60-series)
K=4-speed Manual - Floor
M=5-speed Manual - Floor
P=4-speed Automatic - Floor
R=Standard
N=LX / GX
V=VX / RX / TX / ZX
G=TZ / RZ / VZ
Blank=Standard
X=Turbo
U=DOHC, Carburetor
K=DOHC, EFI
E=OHC, EFI
Blank=Complete Model
3=Cab & Chasis Model
Blank=General Export
W=Europe
Q=Australia
Y=Japan
K=Canada
A=USA
V=G.C.C.
So from above we can conclude that:
FJ70-R__KR
F=F series gasoline engine
J=Jeep/Off-road
7=70-series
0=SWB
R=Right-Hand-Drive
__ (Blank)=Soft Top
K=4-speed manual
R=Standard Equipment
BJ70-R__MR
B=B-series diesel engine
J=Jeep/Off-road
7=70-series
0=SWB
R=Right-Hand-Drive
__ (Blank)=Soft Top
M=5-speed manual
R=Standard Equipment
Specifically;
RKR=RHD, 4/MT, STD
RMR=RHD, 5/MT, STD