D block JG34LL Q & A GT351

I have a D block JG34LL, I just want to know what car it comes from? I know 34 is Fairmont, and I know LL is May 1971, the 34 on a D block has got me stumped as I thought the D block was for GTS only. I also have a GT engine D block GL****C, I am trying to find out what it is out of as I am building a replica and want to build to the same specs. ie colour, trim and so on.