What are RPO Codes?

These are 3 digit identification numbers that will tell you the factory build options of your GM vehicle

Where do I find my RPO Codes?

There is a sticker on the inside of the glovebox that lists all codes

NOTE: If the glovebox liner is not original to the truck then the codes will be WRONG

Here’s an example RPO list for a 1994 GMC K2500 6.5L 4L80E with 4.10 Gear Ratio and Positraction:

M30	4L60E Auto - 6.5L Non-Turbo
MT1	4L80E Auto 4 Speed - 6.5L Turbo
MW3	NV4500 - 5 Speed Manual w/ OD For MW3, the gears are 5.61 for 1st, 3.04 for 2nd, 1.67 for 3rd, 1 for 4th, and 0.73 for 5th.
MT8	NV4500 - 5 Speed Manual w/ OD For MT8, the gears are 6.34 for 1st, 3.44 for 2nd, 1.71 for 3rd, 1 for 4th and 0.73 for 5th

K47	Air Cleaner , High Capacity 1997+