2004R and column shift detents

[Papaloo]

So I have a LWB 1972 Custom Delux C10 with a 350 engine and worn out th350. A friend that does cross country races with junk cars offered me a th350 he had sitting in his shed that worked when he pulled it. Well, I got there and I look at it, and it's not a th350, it's a 2004r from a early 80's Monte Carlo SS. It even had a mechanical speedo out. I was pretty excited because I knew that was pretty much a direct swap for my th350, but for all my searching on here, I have one question I haven't been able to answer. I've never dissasembled an automatic column before so I don't know how the column shift mechanism and detents are setup and work. Do I need to change anything in the column for the 2004R? If I don't change anything in the column, is D the overdrive and then L2 and L1 are 3rd and 2nd gear with no way of manually shifting the tranny into first? Hope this makes sense