I am trying to get a better understanding of how GM RPO codes were developed. For example I assume "M" had something to do with transmissions. Was there a general Letter or Number grouping that options fill under? I put 1970 in the title but would assume while a specific code may mean something different from year to year the letter or number group would remain constant, is that a wrong assumption?

 

Actually, the RPOs main intent remained remarkably consistent from year to year. But the details varied from division to division and from year to year.

For example, FE4 was used to designate a performance suspension -- no matter whether you're talking Olds, Chevy, Buick, Pontiac, etc. and no matter which year. But the individual parts which made up option FE4 varied between divisions and years.

 

Thanks, so if I narrow it down to a 1970 oldsmobile. I would assume that a code that starts with an "A" fill into a certain group, "W" another Group, etc. It is probably not all that important but just want to understand what the group meant. For example did "W" mean performance, did "U" mean electrical or gauges?

 

Jim,

I can't speak for other GM divisions, but Olds typically segregated option types by RPO codes letter.

A = interior and related items (seats, tinted glass, power trunk, seat belts, door locks, etc)
B = Carpet and exterior trim (B80, B85)
C = HVAC (C60 has been manual A/C forever)
D = interior and mirrors (D33, D55)
F = suspension (F41, FE2)
G = rear axle (G80 anti spin, G91, G92 axle ratios)
J = brakes (J50 power brakes, JL2 disk brakes)
K = Engine additions (K30 cruise control, K66 UHV ignition)
L = Engine options (L31, L33, L74, L77)
M = Transmission (M14, M38, M40)
N = Exhaust, steering, and wheels (N10 duals, N33 tilt wheel, N34 sport steering wheel, N47 power steering, N66 SS II wheels)
P = Wheel and tire (PO1 SS I wheels, PK5 G70-14 wide oval tires)
T = Controls (T44 hood lock, T81 nite watch)
U = Electronics (U21 Rally Pac, U35 clock, U57 8-track, U58 stereo)
V = Appearance and protection (V36 bumper guards, V55 luggage rack)
W = Performance options
Y = Cooling and special equipment
Z = Special equipment

 

Joe,
Thanks that is exactly what I was looking for. Is that list located in one of the manuals? I could not find it anywhere. Since I was not sure if it was a GM or Division code category, I assumed the basic group applied across them all, but maybe not.

 

Holy crap statman!