I've been a small block until recently and I'm certainly no expert on big blocks. Question is, can anyone help identify this block?

On the passenger side of the block reads: 2532230.2 DN.RL
On the front passenger side of the block reads: 5R
There is also some letters on the block D P/CD
date: either 3/15/64 or 8/15/64
On the drivers side of the block reads: 2532230.2