NOTE: We strongly recommend that you purchase Part No. 6881010B39-O from Motorola (1-800-422-4210). This is a manual which contains the schematic, parts list, and trouble shooting tips for the Universal Interface. The manual only costs a couple of bucks and would be worth the purchase. You can use the schematic and parts list below until you get the manual. Enjoy!
You also may want to try building this interface instead. It supposedly is a bit simpler and works just fine.