I just bought a 1977 GMC 3/4 ton. It has a 4-speed and a 203 transfer case. it seems like it is in 4 wheel drive all the time, which makes sense since it is a full time t-case; however on the floor next to the shifter there are the following marks. L loc L N H H loc it looks like to me that there is 5 positions for the shifter to me in. I can get it into 3. One being neutral, one all the way forward which is low (2 or 4?), and one all the way back which is high (2 or 4?) obviously all the way back works best for on road. but is it in 4WD at this point? and if so is it posible to get it in 2WD? What do the letters on the shifter plate mean? And how can i tell if it has a 2WD converstion kit on it? I know this is a lot of questions, but i don't know anything about this truck and any help would be great. Thank You.