NOTE: I strongly recommend that you order part number 6880309C92 from Motorola (1-800-422-4210). This is the service manual for the RLN4008B and contains the schematics and parts list for the RIB as well as some cable pinouts. You can use the schematic and parts list below until your service manual arrives.
*Note: We do not have a source for Tango PCB, and we do not have any other formats of this file.
A modification you may be interrested in for the RIB. There have been reports of problems using the RIB on different computers. It looks like one of the problems might be a lack of negative voltage swing on the Busy out and RX (data out) lines back to the computer. You might want to try and change the value of R14 to 1.5k and R11 to 1K.
If you just need to program some of the Radius series of radios like the GP300, GM300, GP350, Maxtrac, Radius Mobile, etc. that only use Ground and Bus+, you can probably get away with building the programming adapter described here.
You could also try using this schematic from http://personales.jet.es/colinlowe/index.htm.
Normally we don't get involved in assisting in the programming of radios other than Motorola's. This time we'll make an exception. This is a schematic of how to make the Motorola RIB usable for programming Vertex Radios.