The 1771-AL modules will need to be replaced with 1771-ASB's. In order to access a remote chassis the the PLC2 used a parallel style of network connection that pre-dates the use of Remote I/O in the PLC5. For this reason the 1771-AL is completely incompatible with the PLC2 processors.
The 1771-DR module is so old it doesn't even appear in current documentation, but from memory I think it was an intelligent I/O module that allowed for a limited amount of I/O logic processing onboard the module, without the need for the processor to be involved. The main reason why this module existed in the days of the PLC2 is that scantimes in the PLC2 could be so slow that the 1771-DR was sold to allow a limited amount of high speed logic to be handled.
When you upgrade the system to a PLC5 if you put the I/O modules associated with any high speed logic in the local chassis of the PLC5 processor, then the scantimes should be fast enough not to need the 1771-DR any more.