For the 1970 Challenger if you have a SE you will have the code 29 in your vin. They droped that code for the 1971 Challenger but offered the A78 package instead. So for your 1970 Challenger for you to have a SE. the third and fourth digits will be 29.

So the body codes for a 1970 Challenger are,
23- hardtop
27- convertible
29- special edition

Bob