You cant. Best bet is to look for the ignition switch which is mounted under the dash instead of in the column.
Even though it is referred to as 69 1/2 they were titled as 1970's. The 1/2 indicates that it was an early model year released when the 1969 cars were still in production. Easiest way to tell is the ignition switch is on the dash on a 69 1/2 on the column on a 70.
I also believe that the original door tag will have been made of aluminum, instead of the common paper variety. Am I right? Thought I saw one or two that way.
VIN breakdown,,, 1st number is model year, starts at 0 for 1970 2nd is assembly plant code 3rd is body serial code 4th is engine code 5th is consectutive unit number http://home.comcast.net/~petebre/maverick/decode/1970.html click the link and it will take you to the decode pages for 1970 model years. Hope this helps, Chad