Retirement tax questions

So, just to be clear I do NOT use a code of PJ like I have read elsewhere? I will only use a code of J?  What is the difference of code 1 and J? They look the same and in a previous 1099 distribution Vanguard used a 1 not J. Also, in the the 1099s I make up for each spouse, do I put the whole distro in box 1 (1200+gain) and in 2a just the gain?  Thanks again.