The 3745 can handle a T3 just fine, but you will need a different interface module. (NM-1A-T3 , NM-1T3/E3, etc.)
Is the 3745 just receiving the traffic, or is it performing additional functions? (Access-lists, VPN termination, BGP, etc.)
Throughput capacity of 225 Kpps for the Cisco 3745.
http://www.cisco.com/en/US/products/hw/routers/ps282/products_white_paper09186a00801bbf09.shtml