[BigSix302]

Junk, Yes I was referring to the door handles in that statement. There are push button type and turn down type handles. Push button were 52 and later. Turn down door handles were 51 and earlier on Advance Design trucks. 1951 is the only year when the door handle was a turn down type and the door had vent wing windows installed. Earlier years has a one piece door window and turn down handles. !952 and later had push button door handles and vent wing windows. A person can make the doors fit what ever year truck they want with some minor mods here and there. So it is sort of difficult to base a year of a truck on the doors only. There are other identifiing styling changes or whatever they are called that can help a guy out. The vin plate attached to the insde drivers door jam will be the best place to start for identification. Chevy and GMC used very different vin numbers. There are decoders out there that will help you if that is your goal.
Use this if you have a GMC vin code. http://www.oldgmctrucks.com/page0010.html